tag:blogger.com,1999:blog-74705940922021118262024-03-13T12:28:17.555+02:00chemistry online | video lectures online | Free education online is possiblemostafahttp://www.blogger.com/profile/06263352237762090405noreply@blogger.comBlogger34125tag:blogger.com,1999:blog-7470594092202111826.post-51256909904663992302009-04-05T11:26:00.000+02:002009-06-04T11:40:03.669+03:00Ionic Bonds<div><div>An ionic bond is the force of attraction between the opposite charges of an ion. One element in an ionic bond loses electrons, and another element must gain the electrons. Some atoms lose electrons to make the outside energy levels become more stable. Atoms become more stable when their outer most energy level has 8 electrons. Pure ionic compounds usually are crystalline solids, liquids, or gases. Many ionic compounds are binary compounds. </div><div>This shows an atom losing an electron. </div><img id="BLOGGER_PHOTO_ID_5343387626513404514" style="DISPLAY: block; MARGIN: 0px auto 10px; WIDTH: 247px; CURSOR: hand; HEIGHT: 291px; TEXT-ALIGN: center" alt="" src="http://2.bp.blogspot.com/_7rZ3Sa3EABQ/SieGvF-MkmI/AAAAAAAAALc/EZTwbKqm6Kg/s400/ionic_bond_animation.gif" border="0" /> <p>Ionic compounds usually have much higher melting and boiling points than covalent compounds.<br />Many ionic compounds dissolve easily in water. The human body must keep a precise amount of ions in order to function properly, these ions are called electrolytes. Without the right concentration of electrolytes your nerve impulses can't travel to your brain.<br />*When you sweat you lose electrolytes. Athletes drink certain drinks to keep the electrolytes balanced*<a href="http://4.bp.blogspot.com/_7rZ3Sa3EABQ/SieGaq8MXSI/AAAAAAAAALU/oTMYoAFHzHA/s1600-h/ionicbond_anim4156456.gif"><img id="BLOGGER_PHOTO_ID_5343387275659861282" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; WIDTH: 235px; CURSOR: hand; HEIGHT: 152px" alt="" src="http://4.bp.blogspot.com/_7rZ3Sa3EABQ/SieGaq8MXSI/AAAAAAAAALU/oTMYoAFHzHA/s400/ionicbond_anim4156456.gif" border="0" /></a></p>In this animation you see two molecules, Potissum (K) and Iodine (I). The electron is transferring from the Potissium (K) ion to the Iodine (I) ion , which is what makes it an ionic compound. Potassium (K) losing an electron to Iodine (I). Potassium Iodide is used to treat thyroid problems in humans.<br /><p></p><br /><p></p></div><br /><p align="center"> <br /><object width="425" height="344"><param name="movie" value="http://www.youtube.com/v/xTx_DWboEVs&hl=en&fs=1"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><br /> <embed src="http://www.youtube.com/v/xTx_DWboEVs&hl=en&fs=1" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="425" height="344"></embed></object><br /><br /><br /><br /></p>mostafahttp://www.blogger.com/profile/06263352237762090405noreply@blogger.com0tag:blogger.com,1999:blog-7470594092202111826.post-43011425176111802262009-04-01T12:30:00.000+02:002009-06-03T12:37:36.853+03:00Chemical formulas<strong>Chemical formula</strong> is a symbolized representation of a chemical compound. It tells us the type of atom(s) (element) present in the compound and in what ratios. Atoms are indicated by their symbols as shown in the periodic table, and the number of atoms are indicated as subscripts. For example, the chemical formula for water is H2O, consists of two hydrogen atoms (H) and one oxygen atom (O).<br /><br />A chemical formula may be written in two ways, as an empirical formula or a molecular formula. The empirical formula is commonly used for both ionic compounds (compounds formed by donation and reception of electrons by participating elements, e.g. NaCl (sodium chloride or common salt) and for covalent compounds (compounds formed by sharing of electrons by participating elements, (e.g. CH4, methane). Molecular formula is commonly used for covalent compounds (e.g., C2H6, ethane).<br /><br />The empirical formula denotes the smallest possible ratio that corresponds to the actual ratio by atoms or formula unit. To construct an empirical formula for an ionic compound, one needs to write the symbol of cations (positively charged ions) first and then the anion (negatively charged ion). Then fulfill the valence requirement of each atom as well as the least possible ratio of atoms present in that compound (e.g., Al2O3 for aluminum oxide). For carbon containing compounds, one needs to write the carbon atom first, then hydrogen atom, followed by other atoms in alphabetical order (e.g., CHCl3 for chloroform).<br /><br />The molecular formula denotes the actual number of different atoms present in one molecule of that compound. In some cases a compound's molecular formula is the same as its empirical formula (e.g., water H2O, ammonia NH3, methane/natural gas CH4) and in others it is an integral multiple of empirical formula (e.g., hydrogen peroxide, empirical formula is HO and molecular formula is H2O2, which is multiple of two of empirical formula). To construct the molecular formula, one needs to follow the steps as for writing empirical formulas, although the actual number of atoms not the smallest ratio is used. Molecular formulas provide the foundation of structure and the molecular weight of a molecule. Yet, it does not provide a complete picture of a molecule, especially for organic molecules. In almost all organic molecules, only part of the molecule (functional groups) participate in a chemical reaction. Also, for one molecular formula, it is possible to have several compounds or isomers (e.g., for C4H10, two compounds; butane and methyl propane) with totally different physical and chemical properties. Hence, organic chemists can use an expanded version of the molecular formula, called the structural formula.<br /><br />A compound's structural formula consists of the actual number of atoms in the compound as well as showing where the chemical bonds are between them. It also provides information about length of chemical bond(s) and angle between chemical bonds. A structural formula has several representations: Lewis dot form, bond-line, stick bond notation, valence orbital notation, and projection form. Firstly, Lewis dot form is the simplest representation of communicating a chemical structure. In Lewis dot form, the atoms are represented by their corresponding symbols, and chemical bonds are represented by a pair of electrons or dots. Each chemical bond is represented by a pair of electrons. Thus single bond, double bond, and triple bonds are represented by two, four, and six dots, respectively. One can easily count the sharing (involved in chemical bond formation) and unsharing electrons (not involved in chemical bond formation). Secondly, "bond-line" notation is similar to Lewis dot form except the bonding electrons are replaced by line(s). Therefore, single, double, and triple bonds are represented by one, two, and three line(s) respectively. Thirdly, "stick-bond" notation is the condensed version of bond-line notation. Each end of a open chain with a single line or a line branching out from a open chain or from a closed cyclic structure represents one methyl (CH3) group. Each corner in an open chain or a cyclic structure represents a methylene (-CH2-) group. Functional groups such as alcohol (-OH), aldehyde (-CHO), acid (-COOH), amine (-NH2), ester (-COOR), etc. are represented by their actual atomic symbols. Fourthly, valence orbital notation, in addition to the above information, reveals the shape of orbital or distribution of electron density around atoms. Fifthly, structure of a compound can be represented in a projected form, because atoms in any molecule occupy space or possess three dimensional structure. Projected form can further be represented in wedge, sawhorse, Newman projection, ball and stick, space filling molecular model, and Fischer projection forms. All these projection forms additionally enable one to see the spatial relationship between atoms and rotation around the connecting chemical bonds. Conceptually, projection forms are an advanced level of learning, but they provide almost a complete insight into structure and properties of a molecule.<br /><p align="center"><br /><br /><embed src="http://www.youtube.com/v/FWozjZ20JyA&hl=" width="425" height="344" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" fs="1"></embed></p>mostafahttp://www.blogger.com/profile/06263352237762090405noreply@blogger.com0tag:blogger.com,1999:blog-7470594092202111826.post-1916989778903492092009-03-31T08:05:00.006+02:002009-06-03T02:45:00.538+03:00Redox Reactions: Dihydroxybenzene Isomers with Ferric Chloride<div style="text-align: center;"><span style="font-weight: bold;">Objective: Distinction between the three Dihydroxbenzene Isomers</span>
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<br /><title>HTML clipboard</title><meta name="GENERATOR" content="Microsoft FrontPage 5.0"><meta name="ProgId" content="FrontPage.Editor.Document"><p style="text-align: left;" dir="ltr"><span style="color: rgb(204, 102, 0); font-weight: bold;font-size:100%;" >Chemicals:</span><span style="color: rgb(0, 0, 204);font-size:1px;" >
<br /></span>catechol resorcinol </p><div style="text-align: left;"> </div><p style="text-align: left;" dir="ltr">hydroquinone </p><div style="text-align: left;"> </div><p style="text-align: left;" dir="ltr">FeCl<sub>3</sub> · 6 H<sub>2</sub>0</p><div style="text-align: left;"><b>Solution of the dihydroxybenzenes:</b> 0.625 g of catechol, resorcinol and hydroquinone, respectively, are dissolved in 20 mL of dist. water. The solutions should be colorless; if needed a "spatula-tip" full of charcoal is added. After shaking the suspension is filtered.
<br /><b>Ferric chloride solution:</b> 1 g FeCl<sub>3</sub> · 6 H<sub>2</sub>0 are dissolved in 150 ml of dist. water.
<br /><p dir="ltr"><span style="color: rgb(204, 102, 0);font-size:100%;" ><b>Glass wares:</b></span><span style="color: rgb(0, 0, 204);font-size:1px;" >
<br /></span>3 conical measures, graduated, 500 mL</p> <p dir="ltr"> 3 glass stirring rods </p> <p dir="ltr">beaker 200 mL </p> <p dir="ltr">3 beakers 40 mL</p> <p dir="ltr"> 3 snap-cap vials 20 mL</p> <p dir="ltr"> volumetric pipet 4 mL </p> <p dir="ltr">volumetric pipet 10 mL </p> <p dir="ltr">2 volumetric pipets 20 mL </p> <p dir="ltr">1 pipette bulb </p> <p dir="ltr">measuring cylinder 100 mL</p><b><span style="color: rgb(204, 102, 0);font-size:100%;" >Experimental procedure:</span>
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<br />Three conical measures are set up as described in the following table.
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<br /></p><basefont>The individual dihydroxybenzene solutions are mixed with aqueous FeCl<sub>3</sub>. 4 mL of FeCl<sub>3</sub> solution are poured into the first conical measure, 10 mL into the second measure and 20 mL into the third measure.
<br /><basefont><span style="color: rgb(204, 102, 0); font-weight: bold;font-size:100%;" >Results:</span>
<br />When treated with aqueous FeCl<sub>3</sub>, the aqueous dihydroxybenzene solutions will show the characteristic color change.
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<br /></p><basefont><span style="font-weight: bold; color: rgb(204, 102, 0);font-size:100%;" >Discussion:</span>
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<br />Like phenol also catechol and resorcinol do form a colored complex with FeCl<sub>3</sub>.
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<br />Hydroquinone is oxidized rapidly to p-benzoquinone, which does not generate a colored complex with FeCl<sub>3</sub>.
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<br /></p><basefont><b>Redox equilibrium between hydroquinone and p-benzoquinone: </b>
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<br /></p>Resorcinol shows no redox reaction with Fe<sup>3+</sup>. The two hydroxy groups in the meta position can not form a quinoid system. Thus a redox reaction between resorcinol and Fe<sup>3+</sup> is impeded.
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<br />Catechol is only partially oxidized to o-benzoquinone.
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<br />mostafahttp://www.blogger.com/profile/06263352237762090405noreply@blogger.com0tag:blogger.com,1999:blog-7470594092202111826.post-16684472532831343592009-03-29T23:48:00.013+02:002009-04-01T14:07:31.511+02:00Substitution Reactions: Azo Coupling <div style="text-align: center;"><span><b>Objective: Electrophilic Aromatic Substitution, Acidic Azo Dyes</b></span><meta content="text/html; charset=utf-8" equiv="Content-Type"><meta name="ProgId" content="Word.Document"><meta name="Generator" content="Microsoft Word 11"><meta name="Originator" content="Microsoft Word 11"><div style="text-align: left; color: rgb(204, 102, 0); font-weight: bold;"><link rel="File-List" href="file:///C:%5CDOCUME%7E1%5Cmostafa%5CLOCALS%7E1%5CTemp%5Cmsohtml1%5C01%5Cclip_filelist.xml"><style> <!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0in; margin-bottom:.0001pt; text-align:right; mso-pagination:widow-orphan; direction:rtl; unicode-bidi:embed; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman";} @page Section1 {size:8.5in 11.0in; margin:1.0in 1.25in 1.0in 1.25in; mso-header-margin:.5in; mso-footer-margin:.5in; mso-paper-source:0;} div.Section1 {page:Section1;} --> </style><span style="color: rgb(204, 102, 0);font-size:100%;" dir="ltr" >
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<br />Chemicals :</span><span lang="AR-SA" style="font-size:100%;"><o:p></o:p></span></div>
<br /><div style="text-align: left;"><span dir="ltr">2 N acetic acid
<br /></span><span dir="ltr">sulfanilic acid
<br /></span><span dir="ltr">ethanol 96 %
<br /></span></div><p style="text-align: left;" dir="rtl" class="MsoNormal"><span dir="ltr">1-naphthol <o:p></o:p></span></p><div style="text-align: left;"></div><p style="text-align: left;" dir="rtl" class="MsoNormal"><span dir="ltr">2-naphthol <o:p></o:p></span></p><div style="text-align: left;"></div><div style="text-align: left;"></div><div style="text-align: left;"><span dir="ltr">phenol </span></div><div style="text-align: left;"><span style=";font-family:';font-size:85%;" >NaNO<sub>2</sub></span>
<br />The following solutions are prepared in advance:
<br /><b>Phenol: </b>15.06 g (160 mmol) dissolved in 400 mL ethanol 96 %
<br /><b>1-naphthol: </b>17.3 g (120 mmol) dissolved in 400 mL ethanol 96 %
<br /><b>2-naphthol:</b> 11.54 g (80 mmol) dissolved in 400 mL ethanol 96 %
<br />The solutions should be colorless; if needed a "spatula-tip" full of activated charcoal powder is added. After shaking, the suspension is filtered.
<br /><b>Reagent solution (Diazo component):</b> 40 mL of 0.5 % aqueous NaNO<sub>2</sub> solution + 40 mL of 0.5 % solution of sulfanilic acid in 2 N acetic acid
<br /><p style="text-align: left;" dir="rtl" class="MsoNormal" align="right"><span style="color: rgb(204, 102, 0);" dir="ltr"><strong>Glass wares:</strong> </span><span style="color: rgb(0, 0, 204);font-size:13px;" dir="ltr" >
<br /></span><span dir="ltr">3 conical measures,</span><span dir="ltr">graduated, 500 mL</span><span dir="ltr"> </span></p><p style="text-align: left;" dir="rtl" class="MsoNormal" align="right"><span dir="ltr">3 glass stirring rods</span></p><p style="text-align: left;" dir="rtl" class="MsoNormal" align="right"><span dir="ltr">5 beakers 50 mL
<br /></span></p><p style="text-align: left;" dir="rtl" class="MsoNormal" align="right"><span dir="ltr">3 beakers 500 mL
<br /></span></p><p style="text-align: left;" dir="rtl" class="MsoNormal" align="right"><span dir="ltr">graduated cylinder 200 mL</span></p><p style="text-align: left;" dir="rtl" class="MsoNormal" align="right"><span style="color: rgb(204, 102, 0); font-weight: bold;">:Experimental procedure </span>
<br />Each of three conical measures is filled with alcoholic solutions of phenol, 2-naphthol and 1-naphthol, respectively. Afterwards the diazo component is added while stirring.
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<br /></p><span style="color: rgb(204, 102, 0); font-weight: bold;">Results:</span>
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<br /></p><span style="color: rgb(204, 102, 0); font-weight: bold;">Discussion:</span>
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<br /><span style="font-family:Symbol;">·</span> Diazotized sulfanilic acid <b>(1)</b> reacts with phenol and the naphtholes forming acid azo dyes <b>(2)</b> The reaction proceeds according to the mechanism of electrophilic aromatic substitution.
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<br />mostafahttp://www.blogger.com/profile/06263352237762090405noreply@blogger.com0tag:blogger.com,1999:blog-7470594092202111826.post-64329728036717323812009-03-18T01:04:00.002+02:002009-03-18T01:53:36.884+02:00Substitution Reactions: Iodoform Reaction<div align="center"><strong>Objectives: Nucleophilic Carbonyl alpha-Substitution,</strong></div><div align="center"><strong>Test for the alpha-Methyl Carbonyl Group</strong></div><div align="left"><strong><span style="color:#cc6600;">Chemicals:</span></strong> </div><div align="left">potassium iodide</div><div align="left">iodine </div><div align="left">ethanol 95% </div><div align="left">2-propanol </div><div align="left">acetone </div><div align="left">2 N NaOH </div><div align="left">Preparation of a 0.2 M iodine solution: </div><div align="left">Using an Erlenmeyer flask, 37.35 g of potassium iodide are dissolved in 375 mL of dist. water. After the addition of 19.05 g of iodine the mixture must be stirred until it is homogeneous. </div><div align="left"><strong><span style="color:#cc6600;">Apparatus and glass wares:</span></strong><br />hot plate<br />2 thermometers<br />3 conical measures, graduated, 500 mL<br />3 glass stirring rods<br />Erlenmeyer flask 500 mL<br />3 beakers 200 mL<br />1 beaker 100 mL<br />2 pipettes 5 mL, graduated in 0.1 mL<br />1 pipette bulb<br />2 snap-cap vials 20 mL<br />2 measuring cylinders 200 mL</div><div align="left"><strong><span style="color:#cc6600;">Experimental procedure:</span></strong></div><div align="left">conical measure 1: 200 ml of 0.2 M iodine solution, warmed up to 40°C </div><div align="left">conical measure 2: 200 ml of 0.1 M iodine solution </div><div align="left">conical measure 3: 200 ml of 0.1 M iodine solution </div><div align="left"><strong>Iodoform test on ethanol:</strong> </div><div align="left">60 mL of ethanol are added to the iodine solution in conical measure 1. Afterwards 150 mL of 2 N NaOH (warmed up to 40°C) are added while stirring. </div><div align="left"><strong>Iodoform test on 2-propanol:</strong></div><div align="left">The iodine solution in conical measure 2 is mixed with 3.8 mL of 2-propanol and 150 mL of 2 N NaOH (room temperature).</div><div align="left"><strong>Iodoform probe on acetone:</strong> </div><div align="left">3.7 mL of acetone and 150 mL of 2 N NaOH (room temperature) are added to the iodine solution in conical measure 3. </div><div align="left"><strong><span style="color:#cc6600;">Results:</span></strong> </div><div align="left">A yellow, crystalline precipitate is formed in each of the three conical measures.</div><div align="left"><strong><span style="color:#cc6600;">Discussion:</span></strong> </div><div align="left">The iodoform reaction is characteristic for methylketones as well as for alcohols (e.g. ethanol, 2-propanol), that can be oxidized to a methyl carbonyl compounds. The iodoform test is a test for the existence of the CH3-CO group in a molecule. The group to which the CH3-CO group is attached can be aryl, alkyl and hydrogen. </div><div align="left">Both ethanol and 2-propanol are oxidized by iodine to give ethanale or acetone. (1). </div><div align="left"></div><div align="left"></div><p><a href="http://tinypic.com/" target="_blank"><img alt="Image and video hosting by TinyPic" src="http://i44.tinypic.com/m8iqma.gif" border="0" /></a> </p><p>When a-methyl carbonyl compounds react with iodine in the presence of a base, the hydrogen atoms on the carbon adjacent to the carbonyl group (a hydrogens) are subsituted by iodine to form tri iodo methyl carbonyl compounds which react with OH - to produce iodoform and carboxylic acid (2): </p><p></p><p><a href="http://tinypic.com/" target="_blank"><img alt="Image and video hosting by TinyPic" src="http://i40.tinypic.com/2l93134.gif" border="0" /></a> </p><p><strong>Reaction mechanism:</strong> </p><p>The hydrogen atoms on the methyl group are slightly acidic and can be removed with hydroxide. The carbanion formed then react with iodine molecules to give a iodide ion and a monoiodonated methyl carbonyl derivate. Introduction of the first iodine atom (owing to its electronegativity) makes the remaining hydrogens of the methyl group more acidic. Hence a base-catalized iodination of a monohalogenated methyl carbonyl derivate occurs at the carbon that is already substituted. Finally a tri iodo methyl carbonyl derivate is formed. </p><p></p><p><a href="http://tinypic.com/" target="_blank"><img alt="Image and video hosting by TinyPic" src="http://i44.tinypic.com/ji2ukn.gif" border="0" /></a> </p><p>The next step is a nucleophilic attack by hydroxide on the carbonyl carbon atom. A carbon-carbon bond cleavage occurs and a triiodomethanide ion departs. The triiodomethanide ion is unusually stable. Its negative charge is dispersed by the three negative iodine atoms. In the last step a proton transfer takes place between carboxylic acid and triiodomethanide ion to form ultimately carboxylate ion and iodoform. </p><p></p><a href="http://tinypic.com/" target="_blank"><img alt="Image and video hosting by TinyPic" src="http://i40.tinypic.com/nd37mt.gif" border="0" /></a><br /><p align="center"><br /><br /><br /><br /><embed src="http://www.youtube.com/v/t3wJfg6Y5s8&hl=" fs="1" width="425" height="344" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true"></embed><br /><br /><br /></p>mostafahttp://www.blogger.com/profile/06263352237762090405noreply@blogger.com0tag:blogger.com,1999:blog-7470594092202111826.post-57953208055325673262009-03-17T12:24:00.003+02:002009-03-28T11:55:33.087+02:00Substitution Reactions: Hydrolysis of tertiary Butyl Halides<div align="center"><strong>Objectives: Nucleophilic Substitution - SN1, </strong></div><div align="center"><strong>Effect of the Leaving Group on Rate</strong></div><div align="left"><br /><strong><span style="color:#cc6600;">Chemicals:<br /></span></strong>2-chloro-2-methylpropane 99 % (M.W. = 92.57, d = 0.851)<br />2-bromo-2-methylpropane 98 % (M.W. = 137.03, d = 1.221)<br />ethanol 96 %<br />0.2 % solution of bromothymol blue in EtOH 96 %<br />2 N NaOH</div><div align="left">If the butyl halides are not perfectly colorless, then they must be distilled. (2-chloro-2-methylpropane, b.p. 51-52°C; 2-bromo-2-methylpropane, b.p. 73,3°C). The butyl halides should be stored in brown bottles. </div><div align="left"><strong><span style="color:#cc6600;">Test solution:</span></strong> </div><div align="left">800 mL of 96 % ethanol + 6.6 mL of 0.2 % solution of bromothymol blue in ethanol 96 % + 6.6 mL of 2 N NaOH + 200 mL of H2O </div><div align="left"><strong><span style="color:#cc6600;">Glass wares:</span></strong><br />2 conical measures, graduated, 500 mL<br />2 glass stirring rods<br />beaker 1500 mL<br />2 snap-cap vials 20 mL<br />2 pipettes 10 mL, graduated in 0.1 mL<br />2 graduated cylinder 500 mL<br />pipette bulb</div><div align="left"><strong><span style="color:#cc6600;">Experimental procedure:</span></strong> </div><div align="left">400 mL of the test solution heated to 60°C are poured into each of two conical measures. Then, 2-chloro-2-methylpropane is added to the solution in conical measure 2 while stirring. Afterwards the solution in conical measure 1 is mixed with 2-bromo-2-methylpropane.<br /><a href="http://tinypic.com/" target="_blank"><img border="0" alt="Image and video hosting by TinyPic" src="http://i42.tinypic.com/2rp2tjp.jpg" width="411" height="101" /></a><br /><strong><span style="color:#cc6600;">Results:</span></strong> </div><div align="left">Approximately 20 seconds after the addition of 2-bromo-2-methylpropane the solution in measure 1 turns abruptly yellow. The solution of bromothymol blue in conical measure 2 remains unchanged. </div><div align="left"><strong><span style="color:#cc6600;">Discussion:</span></strong> </div><div align="left">· Bromothymol blue (transition range: pH 6.0-7.8) is an acid-base indicator that appears blue in an alkaline (base) medium, green in neutral, and yellow in an acidic solution. The solvolysis of the tertiary alkyl halides is revealed by the indicator change from blue to yellow as hydrogen halide is liberated in the reaction. </div><div align="left">· The solvolysis of the tertiary butyl halides in water takes place by anSN1-mechamism . The reaction is unimolecular - only one species is involved in the slow step of the reaction. The reaction rate depends only on the concentration of the alkyl halide (R-X), not the nucleophile: </div><div align="left">R = k [R-X]. </div><div align="left">In an SN1 reaction the key step is the loss of the leaving group to form the intermediate carbocation. This step is the slow, rate determining step of the reaction. The carbocation is then attacked by a nucleophile in a fast second step to form the product. The more stable the carbocation is, the easier it is to form, and the faster the SN1 reaction will be. The planar, trigonal carbocation may be attacked equally well from either side by a nucleophile. As a consequence, an SN1 reaction leads to a racemization, in which both retention and inversion of configuration at a chiral center occur to the same extent. Optically active tertiary haloalkanes produce a mixture of two enantiomers (mirror image isomers).<br /><a href="http://tinypic.com/" target="_blank"><img border="0" alt="Image and video hosting by TinyPic" src="http://i43.tinypic.com/2ldhr0g.gif" width="554" height="219" /></a><br />· In the rate-determining step of SN1 reactions, the alkyl halide (R-X) is cleaved into a positively charged carbocation and a negatively charged leaving group. The reaction not only on the polarity of the solvent and on the stability of the carbocation, but also on the stability of the leaving group. The more stable the leaving group is, the more easily the C-X bond is also cleaved, the higher the reaction rate is. Conjugated bases of strong acids are good leaving groups. The experiment above shows that bromide ion is a better leaving group than the chloride ion. Bromide is a weaker base than chloride. Therefore the weaker base is more stable and thus more easily formed.<br />Relative hydrolysis rateg of R-X (R = tertiary alkyl group)<br />X = I > Br > Cl<br /><p align="center"><br /><br /><object width="425" height="344"><param name="movie" value="http://www.youtube.com/v/NFio9Hi3DFQ&hl=en&fs=1"><param name="allowFullScreen" value="true"><param name="allowscriptaccess" value="always"><br /> <embed src="http://www.youtube.com/v/NFio9Hi3DFQ&hl=en&fs=1" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="425" height="344"></embed></object><br /><br /><br /><br /><br /></p></div>mostafahttp://www.blogger.com/profile/06263352237762090405noreply@blogger.com0tag:blogger.com,1999:blog-7470594092202111826.post-65147900849125865952009-03-16T11:47:00.002+02:002009-03-16T12:14:41.491+02:00Substitution Reactions: Hydrolysis of Butyl Bromide Isomers<div align="center"><strong>Objective: Nucleophilic Substitution - SN1 and SN2</strong></div><div align="left"><strong><span style="color:#cc6600;">Chemicals:</span></strong></div><div align="left">1-bromobutane (M = 137.03, d =1.2785) </div><div align="left">2-bromobutane (M = 137.03, d = 1.2585) </div><div align="left">2-bromo-2-methylpropane (M = 137.03, d = 1.221) </div><div align="left">bromothymol blue ethanol 99 %</div><div align="left">0.1 N NaOH</div><div align="left">If the butylbromides are not perfectly colorless, then they must be distilled. (1-bromobutane, b.p. 101.6°C; 2-bromobutane, b.p. 91.2°C; 2-bromo-2-methylpropane, b.p. 73.3°C). The butylbromides are to be stored in brown bottles. </div><div align="left"><strong><span style="color:#cc6600;">Apparatus and glass wares:</span></strong></div><div align="left">heating mantle</div><div align="left">thermometer </div><div align="left">3 conical measures, graduated, 500 mL</div><div align="left">3 glass stirring rods </div><div align="left">round bottom flask 1.5 L </div><div align="left">3 snap-cap vials 20 mL</div><div align="left">graduated cylinder 500 mL </div><div align="left">graduated cylinder 100 mL</div><div align="left">volumetric pipet 2 mL</div><div align="left">pipet ball</div><div align="left"><strong><span style="color:#cc6600;">Experimental procedure:</span></strong></div><div align="left">The reagent solution is heated to 60°C using a heating mantle and a round bottom flask. Measured quantities of the butylbromide isomers are available in snap-cap vials: </div><div align="left">Vial 1: 16 g of 1-bromobutane </div><div align="left">Vial 2: 16 g of 1-bromobutane </div><div align="left">Vial 3: 16 g of 2-bromo-2-methylpropane </div><div align="left">300 mL of the reagent solution heated to 60°C are placed in each of three conical measures. </div><div align="left">1-bromobutane is poured into the third conical measure while stirring with a glass rod. 2-bromobutane and tertiary butylbromide, respectively, is added with stirring to the reagent solutions in the conical measures 2 or 1, respectively. </div><div align="left"><strong><span style="color:#cc6600;">Results:</span></strong> </div><div align="left">The solution in conical measure 1 turns abruptly yellow. After some time, the solutions in the measures 2 and 3 appear green, before the color turns to yellow. 1-bromobutane (conical measure 3) reacts very slowly. </div><div align="left"><strong><span style="color:#cc6600;">Discussion:</span></strong> </div><div align="left">· Bromothymol blue (transition range: pH 6.0-7.8) is an acid-base indicator that appears blue in an alkaline (base) medium, green in neutral, and yellow in an acidic solution. </div><div align="left">· The hydrolysis of the butyl bromide isomers is revealed by the indicator change from blue to yellow as hydrogen bromide is liberated in the reaction. The color change of the indicator permits the proof of the different reactivity of the alkyl halides. A heterolytic fission of the C-Br bond occurs. The reactivity is rising in the order 1-bromobutane <> </div><div align="left">On the basis of mechanistical investigations can be proven: </div><div align="left">· The hydrolysis of primary halides proceeds by an SN2-mechanism . The reaction is bimolecular, i.e. two species are involved in the rate-determining step. The reaction rate depends on both the alkyl halide's (R-X) and the nucleophile's (Nu) concentration: R = k [R-X][Nu]. </div><div align="left"></div><a href="http://tinypic.com/" target="_blank"><div align="left"><br /><img height="120" alt="Image and video hosting by TinyPic" src="http://i43.tinypic.com/14uvtq9.jpg" width="553" border="0" /></a><br />The SN2 (bimolecular nucleophilic substitution) involves rear-side attack of a nucleophile at the carbon atom, opposite to the leaving group being displaced. The incoming group replaces the leaving group in one step. Bond making and breaking occurs simultaneously. The "pentacoordinated" transition state of the SN2 reaction is a trigonal bipyramid with the nucleophile and the leaving group located at the tops of the pyramids and the three remaining substituents located at the corners of the trigonal base. As the incoming nucleophile begins to bond with the carbon, the leaving group is departing with the bonding electrons. As a result of the mechanism, the three remaining substituents are rejected. The inversion of configuration resembles the way an umbrella turns inside out in a strong gust of wind (1). If the substrate under nucleophilic attack is chiral, this leads to an inversion of stereochemistry, called the "Walden Inversion". </div><div align="left">· The solvolysis of the tertiary butyl halides in water takes place by anSN1-mechamism . The reaction is unimolecular - only one species is involved in the slow step of the reaction. The reaction rate depends only on the concentration of the alkyl halide (R-X), not the nucleophile: R = k [R-X]. </div><a href="http://tinypic.com/" target="_blank"><div align="left"><br /><img height="218" alt="Image and video hosting by TinyPic" src="http://i39.tinypic.com/mrwqis.gif" width="578" border="0" /></a><br /><br />In an SN1 reaction the key step is the loss of the leaving group to form the intermediate carbocation. This step is the slow, rate determining step of the reaction. The carbocation is then attacked by a nucleophile in a fast second step to form the product. The more stable the carbocation is, the easier it is to form, and the faster the SN1 reaction will be. The planar, trigonal carbocation may be attacked equally well from either side by a nucleophile (2).</div><div align="left"> As a consequence, an SN1 reaction leads to a racemization, in which both retention and inversion of configuration at a chiral center occur to the same extent. This effect results in a mixture of two enantiomers (mirror image isomers). </div><div align="left">· The hydrolysis mechanism of the secondary butylbromide depends very strongly on the reaction conditions. </div><div align="left"></div><div align="left"><br /></div><br /><p align="center"><br /><br /><br /><embed src="http://www.youtube.com/v/y6SSTMBgMXs&hl=" fs="1" width="425" height="344" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true"></embed><br /><br /><br /><br /></p>mostafahttp://www.blogger.com/profile/06263352237762090405noreply@blogger.com0tag:blogger.com,1999:blog-7470594092202111826.post-18966341755966445002009-03-15T20:55:00.013+02:002009-03-15T22:00:59.171+02:00Substitution Reactions: Reaction of Butylbromide Isomers with AgNO3<div align="center"><strong>Objective: Nucleophilic Substitution - SN1 and SN2 </strong></div><br /><br /><div align="left"><strong><span style="color:#cc6600;">Chemicals:</span></strong> </div><div align="left">1-bromobutane (M.W. = 137.03, d =1.2785)</div><div align="left">2-bromobutane (M.W. = 137.03, d = 1.2585) </div><div align="left">2-bromo-2-methylpropane (M.W. = 137.03, d = 1.221)</div><div align="left">ethanol 95 %</div><div align="left">0.1 M AgNO3 solution</div><div align="left">If the butylbromides are not perfectly colorless, then they must be distilled. (1-bromobutane, b.p. 101.6°C; 2-bromobutane, b.p. 91.2°C; 2-bromo-2-methylpropane, b.p. 73.3°C). The butylbromides are to be stored in brown bottles. </div><div align="left"><strong><span style="color:#cc6600;">Apparatus and glass wares:</span></strong></div><div align="left">heating mantle</div><div align="left">thermometer </div><div align="left">3 conical measures, graduated, 500 mL</div><div align="left">3 glass stirring rods </div><div align="left">round bottom flask 1.5 L </div><div align="left">3 snap-cap vials 10 mL </div><div align="left">measuring cylinder 500 mL</div><div align="left">measuring cylinder 25 mL</div><div align="left"><strong><span style="color:#cc6600;">Experimental procedure:</span></strong> </div><div align="left">1.2 L of ethanol are heated to 60°C using a heating mantle and a round bottom flask. </div><div align="left">Measured quantities of the butylbromide isomers are available in sap-cap vials: </div><div align="left">Vial 1: 8.8 g (64 mmole) 1-bromobutane </div><div align="left">Vial 2: 8.8 g (64 mmole) 2-bromobutane</div><div align="left">Vial 3: 8.8 g (64 mmole) 2-bromo-2-methylpropane </div><div align="left">20 mL of aqueous 0.1 M AgNO3 solution are added to each of three conical measures containing 400 mL of ethanol heated to 60°C. 1-bromobutane is poured into the first conical measure while stirring with a glass rod. 2-bromobutane and tertiary butylbromide, respectively, is added simultaneously with stirring to the alcoholic solutions of the conical measures 2 and 3, respectively. </div><div align="left"><strong><span style="color:#cc6600;">Results:</span></strong> </div><div align="left">Reaction is indicated by the formation of a pale yellow precipitate. The tertiary halide 2-bromo-2-methylpropane immediately forms a light yellow precipitate. 2-bromobutane reacts next - a turbidity of the reaction mixture can be observed within a few of seconds. After a couple of minutes, 1-bromobutane begins to react with AgNO3 solution. <p align="left"><br /><br /><a href="http://tinypic.com/" target="_blank"><br /><img height="273" alt="Image and video hosting by TinyPic" src="http://i41.tinypic.com/2w20m8k.jpg" width="553" border="0" /></a><br />· The rate, at which the heterolytic fission of the C-Br bond occurs, rises in the order 1-bromobutane < 2-bromobutane < tertiary butylbromide.The three reactions have the same nucleophile and the same leaving group. Hence, the rates of the SN-reactions will depend on the different structures of the butylbromide isomers.<br />· On the basis of mechanistical investigations can be proven: The primary halide reacts according to the SN2-mechanism (1), the tertiary halide according to the SN1-mechamism (2). The hydrolysis mechanism of the secondary butylbromide depends very strongly on the reaction conditions.<br /></p><p align="center"><br /><a href="http://tinypic.com/" target="_blank"><img height="121" alt="Image and video hosting by TinyPic" src="http://i42.tinypic.com/2nr3961.jpg" width="554" border="0" /></a><br /><br /><a href="http://tinypic.com/" target="_blank"><img height="218" alt="Image and video hosting by TinyPic" src="http://i42.tinypic.com/16a194j.gif" width="546" border="0" /></a><br /><br /><br /><br /></p><br /><br /><p align="center"><br /><br /><embed src="http://www.youtube.com/v/eDHyWxSQi7U&hl=" width="425" height="344" type="application/x-shockwave-flash" fs="1" allowfullscreen="true" allowscriptaccess="always"></embed><br /><br /><br /><br /></p></div>mostafahttp://www.blogger.com/profile/06263352237762090405noreply@blogger.com0tag:blogger.com,1999:blog-7470594092202111826.post-29528565562535471822009-03-14T23:18:00.007+02:002009-03-15T00:54:19.415+02:00Addition of 2,4-Dinitrophenyl hydrazine to Aldehydes and Ketones<div align="center"><strong>Objectives: Nucleophilic Addition to the Carbonyl Function,</strong></div><br /><div align="center"><strong>Addition-Elimination</strong><br /></div><br /><div align="left"><strong><span style="color:#cc6600;">Chemicals:</span></strong> </div><div align="left">2,4-dinitrophenyl hydrazine<br />acetone<br />benzaldehyde<br />conc HCl<br />2 N HCl<br /><strong><span style="color:#cc6600;">Apparatus and glass wares:</span></strong><br />2 conical measures, 350 mL<br />porcelain dish<br />beaker 800 mL<br />2 glass stirring rods<br />2 snap-cap vials 10 mL<br /><strong><span style="color:#cc6600;">Reagent solution:</span></strong><br />1.2 g of 2,4-dinitrophenyl hydrazine are doused with 12 mL of conc. HCl in a porcelain dish (fume hood!). The formed light yellow hydrochloride is mixed to produce a slurry that is poured into 600 mL of 2 N HCl while stirring. The hydrochloride should be perfectly dissolved.<br /><strong><span style="color:#cc6600;">Experimental procedure:</span></strong><br />Two conical measures are each filled with 300 mL of the hydrochloric acid solution of 2,4-dinitrophenyl hydrazine. 10 mL of acetone and benzaldehyde, respectively, are slowly added to the dinitrophenyl hydrazine solutions while stirring.<br /><strong><span style="color:#cc6600;">Results:</span></strong><br />Copious crystalline precipitates are formed. Acetone gives a yellow precipitate and benzaldehyde gives a orange yellow precipitate.<br /><strong><span style="color:#cc6600;">Discussion:</span></strong> <a href="http://1.bp.blogspot.com/_7rZ3Sa3EABQ/Sbw0xRfNS5I/AAAAAAAAAJ4/PccVt1SsVc8/s1600-h/clip_image002.jpg"><img id="BLOGGER_PHOTO_ID_5313179681502874514" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; WIDTH: 400px; CURSOR: hand; HEIGHT: 144px" alt="" src="http://1.bp.blogspot.com/_7rZ3Sa3EABQ/Sbw0xRfNS5I/AAAAAAAAAJ4/PccVt1SsVc8/s400/clip_image002.jpg" border="0" /></a><br />The formation of this precipitate is a positive test for the carbonyl group of ketones and aldehydes. The ketone or aldehyde is converted to its hydrazone by reaction with dinitrophenyl hydrazine.<br />Apositive test is a yellow, orange, or red precipitate. Small crystals made from unconjugated aldehydes and ketones give precipitates toward the yellow end of the scale. Large crystals made from conjugated compounds tend to be more red.<br />Hydrazones have a sharp melting point and can assist in identifying carbonyl compounds.<br /><br /><br /></div><p align="center"><br /><br /><br /><br /><br /><br /><embed src="http://www.youtube.com/v/7aKvYLPR4zQ&hl=" width="425" height="344" type="application/x-shockwave-flash" fs="1" allowscriptaccess="always" allowfullscreen="true"></embed><br /><br /><br /><br /></p>mostafahttp://www.blogger.com/profile/06263352237762090405noreply@blogger.com0tag:blogger.com,1999:blog-7470594092202111826.post-43577766845738721682009-03-13T09:39:00.008+02:002009-03-14T23:59:58.457+02:00Reaction of Cyclohexene with Bromine and Potassium Permanganate<div align="center"><strong>Objective: Test for the C=C Double Bond</strong></div><p><br /><strong><span style="color:#cc6600;">Chemicals:</span></strong><br />cyclohexene<br />benzene<br /><sub>10</sub>-2 M aqueous bromine (1.28 g bromine / 800 mL H2O)<br /><sub>10</sub>-4 M aqueous KMnO4 (12.6 mg KMnO4 / 800 mL H2O)<br /><strong><span style="color:#cc6600;">Apparatus and glass wares:</span></strong><br />4 graduated cylinders with stopper 500 mL<br />2 pipettes 1 mL, graduated in 0.1 mL<br />2 pipet bulbs<br />4 snap-cap vials 10 mL<br /><strong><span style="color:#cc6600;">Experimental procedure: </span></strong><br />Two snap-cap vials contain 0.75 mL benzene. 0.8 mL cyclohexene are pipetted into each of two further snap-cap vials. Two collecting cylinders are each filled with 10-2 M aqueo<a href="http://2.bp.blogspot.com/_7rZ3Sa3EABQ/SboPTtPTUzI/AAAAAAAAAJQ/KnSGjrSQ77k/s1600-h/clip_image002.jpg"><img id="BLOGGER_PHOTO_ID_5312575541672629042" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; WIDTH: 400px; CURSOR: hand; HEIGHT: 99px" alt="" src="http://2.bp.blogspot.com/_7rZ3Sa3EABQ/SboPTtPTUzI/AAAAAAAAAJQ/KnSGjrSQ77k/s400/clip_image002.jpg" border="0" /></a>us bromine and two further cylinders are filled with 10-4 M aqueous KMnO4. The solutions are mixed with benzene and cyclohexene, respectively<br />The stoppered cylinders are vigorously shaken.<br /><strong><span style="color:#cc6600;">Results:</span></strong><br />Benzene reacts neither with aqueous bromine nor with permanganate solution. Cyclohexene reacts with both aqueous bromine and permanganate. The solution of bromine is decolorized and purple permanganate turns brown.<br /><strong><span style="color:#cc6600;">Discussion:</span></strong><br />The decolorization of bromine water is often used as a test for a carbon-carbon double bond. Bromine undergoes electrophilic addition to the double bond of alkenes. In non-aqueous solvents such as carbon tetrachloride, this gives the di-bromo product. For example, reaction with ethylene will produce 1,2-dibromoethane. When used as bromine water, the corresponding bromohydrin is formed instead.<a href="http://3.bp.blogspot.com/_7rZ3Sa3EABQ/SboQOQwF6lI/AAAAAAAAAJY/9OeSgJfx5hs/s1600-h/brom-e.gif"><img id="BLOGGER_PHOTO_ID_5312576547637815890" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; WIDTH: 542px; CURSOR: hand; HEIGHT: 208px" alt="" src="http://3.bp.blogspot.com/_7rZ3Sa3EABQ/SboQOQwF6lI/AAAAAAAAAJY/9OeSgJfx5hs/s400/brom-e.gif" border="0" /></a><br /><a href="http://3.bp.blogspot.com/_7rZ3Sa3EABQ/SboQOQwF6lI/AAAAAAAAAJY/9OeSgJfx5hs/s1600-h/brom-e.gif"></a><br /><a href="http://3.bp.blogspot.com/_7rZ3Sa3EABQ/SboQOQwF6lI/AAAAAAAAAJY/9OeSgJfx5hs/s1600-h/brom-e.gif"></a><br /><br /><a href="http://3.bp.blogspot.com/_7rZ3Sa3EABQ/SboQOQwF6lI/AAAAAAAAAJY/9OeSgJfx5hs/s1600-h/brom-e.gif"></a><br /><br /><a href="http://3.bp.blogspot.com/_7rZ3Sa3EABQ/SboQOQwF6lI/AAAAAAAAAJY/9OeSgJfx5hs/s1600-h/brom-e.gif"></a><br /><br /></p><p>On approaching the electron dense area of the p bond of cyclohexene, the bromine molecule becomes polarized. The electron density of the bromine is shifted, so that one bromine is partially positive and the other is partially negative charged. The Br-Br bond is heterolytically cleaved. The positively charged bromine atom acts as an electrophile, reacting with the C=C double bond. A cyclic bromonium ion is formed. The subsequent attack of the bromide ion on the three-membered ring can proceed only from the back-side, because the front-side attack is sterically hindered. The result is formation of a mixture of two enantiomeric compounds of trans-1,2-dibromocyclohexane. (1). When other nucleophiles such as water or alcohol are existing, these may attack the cyclic bromonium ion to give an alcohol or an ether (2).<br /><br />Also the permanganate hydroxylation is used as a qualitative test for the presence of an alkene (Bayer test). Permanganate converts cyclohexene into a diol. In the course of the reaction purple permanganate is reduced to brown manganese dioxide (3).<br /><a href="http://3.bp.blogspot.com/_7rZ3Sa3EABQ/SboQshMAibI/AAAAAAAAAJg/7D7NOQXGElA/s1600-h/perm1e.gif"><img id="BLOGGER_PHOTO_ID_5312577067445946802" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; WIDTH: 553px; CURSOR: hand; HEIGHT: 163px" alt="" src="http://3.bp.blogspot.com/_7rZ3Sa3EABQ/SboQshMAibI/AAAAAAAAAJg/7D7NOQXGElA/s400/perm1e.gif" border="0" /></a><br /><a href="http://2.bp.blogspot.com/_7rZ3Sa3EABQ/SboQ9Ej5W6I/AAAAAAAAAJo/X9juk1RGEdk/s1600-h/perm2e.gif"><img id="BLOGGER_PHOTO_ID_5312577351819287458" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; WIDTH: 555px; CURSOR: hand; HEIGHT: 124px" alt="" src="http://2.bp.blogspot.com/_7rZ3Sa3EABQ/SboQ9Ej5W6I/AAAAAAAAAJo/X9juk1RGEdk/s400/perm2e.gif" border="0" /></a><br /></p><p></p><p></p><p align="center">Since a syn-hydroxylation takes place, the reaction is thought to involve the formation of an intermediate cyclic hypomanganate ester which is readily hydrolyzed under the reaction conditions to yield the glycol (4). Experiments with 18O-labelled permanganate demonstrate, that the two oxygen atoms of glycol originate on the permanganate and not on the solvent.<br /><br /><br /><br /><br /><embed src="http://www.youtube.com/v/bowWOuOs_SU&hl=" width="425" height="344" type="application/x-shockwave-flash" fs="1" allowscriptaccess="always" allowfullscreen="true"></embed><br /><br /><br /></p>mostafahttp://www.blogger.com/profile/06263352237762090405noreply@blogger.com0tag:blogger.com,1999:blog-7470594092202111826.post-82512677990974880022009-03-09T22:09:00.012+02:002009-03-11T20:37:43.645+02:00Addition of Bisulfite to Aldehydes<div align="center"><strong>Objective: Nucleophilic Addition to the Carbonyl Function</strong></div><div align="left"><br /><span style="color:#cc6600;"><strong>Chemicals:<br /></strong></span>benzaldehyde<br />sodium disulfite</div><div align="left"></div><p><strong><span style="color:#cc6600;">Apparatus and glass wares:</span></strong><br />3 graduated cylinder with stopper 500 mL<br />beaker 200 mL<br />Erlenmeyer flask with stopper 250 mL<br />temperature probe<br />temperature measuring device </p><p><strong><span style="color:#cc6600;">Experimental procedure:</span></strong><br />Using an Erlenmeyer flask with stopper, 108 g of sodium disulfite are dissolved in 200 mL of dist. water. Sodium disulfite dissolves in water to form bisulfite ions. The solution of disulfite is poured into a graduated cylinder containing 116 mL of benzaldehyde. The stoppered cylinder is shaken vigorously. After removing the stopper a temperature probe connected to a temperature measuring device is inserted into the reaction mixture.<br /><strong><span style="color:#cc6600;">Results:</span></strong> </p><div align="left">With an exothermic reaction the content of the graduated cylinder solidifies.<br /><strong><span style="color:#cc6600;">Discussion:</span></strong><br />The characteristic reaction of aldehydes and ketones is addition across the carbon-oxygen double bond. Because of polarization of the C=O bond, the carbon atom of the carbonyl group becomes electron-deficient, acquiring a partial positive charge. This makes it susceptible to nucleophilic attack by an electron-rich chemical species. In the present case, bisulfite ion is added to the electrophilic center. Since the sulfur atom of bisulfite has an unshared pair of electrons it can act as a nucleophile and form a bond to c<a href="http://1.bp.blogspot.com/_7rZ3Sa3EABQ/SbV6UN3Jh1I/AAAAAAAAAI4/jLWIgXFoax4/s1600-h/clip_image002.jpg"></a>arbonyl carbon(1) </div><p align="center"><a href="http://3.bp.blogspot.com/_7rZ3Sa3EABQ/SbV7sOu7X6I/AAAAAAAAAJA/Q7n2eaqLge8/s1600-h/aldehyde-e.gif"><img id="BLOGGER_PHOTO_ID_5311287335352754082" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; WIDTH: 385px; CURSOR: hand; HEIGHT: 121px" alt="" src="http://3.bp.blogspot.com/_7rZ3Sa3EABQ/SbV7sOu7X6I/AAAAAAAAAJA/Q7n2eaqLge8/s400/aldehyde-e.gif" border="0" /></a></p><a href="http://3.bp.blogspot.com/_7rZ3Sa3EABQ/SbV7sOu7X6I/AAAAAAAAAJA/Q7n2eaqLge8/s1600-h/aldehyde-e.gif"></a><p align="center"><a href="http://3.bp.blogspot.com/_7rZ3Sa3EABQ/SbV7sOu7X6I/AAAAAAAAAJA/Q7n2eaqLge8/s1600-h/aldehyde-e.gif"></a></p><a href="http://3.bp.blogspot.com/_7rZ3Sa3EABQ/SbV7sOu7X6I/AAAAAAAAAJA/Q7n2eaqLge8/s1600-h/aldehyde-e.gif"></a><p align="center"><a href="http://3.bp.blogspot.com/_7rZ3Sa3EABQ/SbV7sOu7X6I/AAAAAAAAAJA/Q7n2eaqLge8/s1600-h/aldehyde-e.gif"></a></p><p align="center"><a href="http://3.bp.blogspot.com/_7rZ3Sa3EABQ/SbV7sOu7X6I/AAAAAAAAAJA/Q7n2eaqLge8/s1600-h/aldehyde-e.gif"></a></p><p align="left">In general, aldehydes are more reactive than ketones. There is a combination of steric hindrance and inductive effects that makes ketones to react slower than aldehydes (2). </p><p align="left">- Bulky alkyl groups sterically hinder the approach of nucleophile.<br />-The electronic effects of alkyl substituents are weakly electron donating. So they make the C atom in carbonyl less electrophilic</p>The addition of bisulfite is usually employed to pu<a href="http://2.bp.blogspot.com/_7rZ3Sa3EABQ/SbV87Yw5meI/AAAAAAAAAJI/J8gZZA--gVw/s1600-h/aldehyde2-e.gif"><img id="BLOGGER_PHOTO_ID_5311288695255046626" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; WIDTH: 407px; CURSOR: hand; HEIGHT: 174px" alt="" src="http://2.bp.blogspot.com/_7rZ3Sa3EABQ/SbV87Yw5meI/AAAAAAAAAJI/J8gZZA--gVw/s400/aldehyde2-e.gif" border="0" /></a>rify aldehydes. Aldehydes are isolated from reaction mixtures through its bisulfite derivatives. The addition compound can be split easily to regenerate the aldehyde by treating it with either dilute mineral acid or dilute alkali.<br /><br /><br /><br /><p align="center"><br /><br /><br /><br /><br /><br /><embed src="http://www.youtube.com/v/JHF31E8BV4c&hl=" width="425" height="344" type="application/x-shockwave-flash" fs="1" allowscriptaccess="always" allowfullscreen="true"></embed><br /><br /><br /><br /><br /><br /><br /><p align="center"></p><br /><br /><br /><br /><p></p>mostafahttp://www.blogger.com/profile/06263352237762090405noreply@blogger.com0tag:blogger.com,1999:blog-7470594092202111826.post-78121580693819560982009-03-05T14:59:00.000+02:002009-03-05T14:59:00.788+02:00Combustion Engineering<strong><em><span style="color:#ff0000;">Combustion Engineering</span></em></strong><br />Summary :<br /><strong>a-Combustion :</strong><br />For the combustion of 1Kg fuel a certain amount of oxygen is required .<br /><strong>b-Kiln gas :</strong><br />The kiln gas consists of :<br />1-Combustion products .<br />2-Excess air of combustion .<br />3-False air .<br />4-Gas from raw meal .<br /><strong>c-Analysis of kiln gases :</strong><br />The orsat-analysis is used to analyze the dry kiln gases , from orsat-analysis we get :<br />1-Excess air factor ( n ) .<br />2-Incomplete combustion .<br />3-Heat consumption .<br />4-False air .<br /><strong><em><span style="color:#ff0000;">Combustion</span></em></strong><br /><strong>A-Fuel</strong> :<br />We have three types of fuels :<br />a-Gaseous fuels .<br />b-Liquid fuels .<br />c-Solid fuels .<br />The combustible elements that characterize fuels are carbon , hydrogen and sulfer .The complete combustion of carbon gives carbon dioxide and hydrogen gives water .The products of complete combustion of fuel are CO2 ,H2O ,N2 and O2 .The presence of CO indicates incomplete combustion .<br /><strong>B- Heat of combustion</strong> :<br />Chemical change is accompanied by absorption of heat .Heat values that generated when 1Kg of fuel is completely burned .<br />Purpose Of The Gas Analysis<br />The knowledge of the gas composition in a cement plant is important to control the firing of kiln .The following points can be determined :<br />1-How complete the combustion of fuel .<br />2-How much excess air .<br />3-False air .<br />4-Specific consumption .mostafahttp://www.blogger.com/profile/06263352237762090405noreply@blogger.com0tag:blogger.com,1999:blog-7470594092202111826.post-43167451521391960062009-03-03T14:40:00.000+02:002009-03-03T14:40:00.861+02:00Portland Cement Clinker<strong><em><span style="color:#ff0000;">Portland Cement Clinker</span></em></strong><br /><strong>1 – Clinker Mineralogy .<br /></strong> a – The phases which should theoretically be present in a cooled clinker of this composition .<br /> b – The quantity of each phase which should be present :<br /> I – C3S<br /> II – C2S<br /> III – C3A<br /> IV – C4AF<br /> Phase diagram CaO-SiO2-Al2O3 .<br /> Phase diagram CaO-SiO2-Al2O3-Fe2O3<br /><strong>2 – Real Clinker Minerals .</strong><br /> What are the real chemical compositions of the clinker minerals ?<br /> Pure compounds C3S , C2S , C3A not occur in this simple form , but contain oxides such as MgO , Na2O , K2O , Fe2O3 and Al2O3 .<br /> Using analytical techniques :<br /> a – Electron microprobe analyzer .<br /> b – Energy dispersive analyzer .<br /><strong>Polymorphic modification of clinker minerals<br /></strong>We find that not only chemical composition vary clinker minerals , but some clinker phase also exist in different polymorphic forms , which can exhibit different physical properties .<br /> a - C3S alite<br /> Have 6 polymorphic modification between room temperature and 11000C . The changing appear in the lattice structure .<br />b - C2S belite ( β-C2S ) .<br /> Have 5 modifications between room temperature and 15000C (γ , β ,α) . The change β to γ and γ to α are irreversible and slow .<br /> c - C3A .<br /> C3A present as a cubic lattice , but Na2O are incorporated within the lattice forming orthorhombic , monoclinic and tetragonal modification but they differ in their reactivates .<br /> d - C4AF .<br /> Pure C4AF is not found .<br /><strong>Quantitative clinker mineralogy</strong><br />A – Calculation of potential clinker composition . By Bogue , which consider chemical equilibrium has been attained .<br /> 1 – Fe2O3+Al2O3+CaO= C4AF<br /> 2 - Al2O3+CaO= C3A<br /> 3 – SO3+CaO=CaSO4<br /> 4 – CaO+SiO2= C2S<br /> 5 - C2S+CaO= C3S<br /> 6 – MgO free .<br /># C3S=4.07*CaO-7.6*SiO2-6.72*Al2O3-1.43*Fe2O3-2.85*SO3<br /><br /> #C2S=2.87*SiO2-.754*C3Smostafahttp://www.blogger.com/profile/06263352237762090405noreply@blogger.com0tag:blogger.com,1999:blog-7470594092202111826.post-53069040270122725952009-03-01T10:33:00.000+02:002009-03-01T10:33:00.615+02:00Kiln Systems<div><strong><em><span style="color:#ff0000;">Kiln Systems</span></em></strong> <a href="http://2.bp.blogspot.com/_7rZ3Sa3EABQ/Safe23ehHaI/AAAAAAAAAIQ/MYNqaiLbdCc/s1600-h/images.jpg"><img id="BLOGGER_PHOTO_ID_5307455720065670562" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; WIDTH: 148px; CURSOR: hand; HEIGHT: 137px" alt="" src="http://2.bp.blogspot.com/_7rZ3Sa3EABQ/Safe23ehHaI/AAAAAAAAAIQ/MYNqaiLbdCc/s320/images.jpg" border="0" /></a><br />All kiln systems for burning cement clinker are based on the rotary kiln principal . <br />At first classification of kiln can be made according to water content of kiln feed :<br />1 – Dry process > 1 % water<br />2 – Semi-dry process 10 – 12 % water<br />3 – Semi-wet process 17 – 21 % water<br />4 – Wet process 25 – 40 % water<br /><strong><span style="color:#ff0000;">Dry process</span></strong> <a href="http://2.bp.blogspot.com/_7rZ3Sa3EABQ/SafejCPY8aI/AAAAAAAAAII/BYH0PJfxhrs/s1600-h/images.jpg"><img id="BLOGGER_PHOTO_ID_5307455379357626786" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; WIDTH: 150px; CURSOR: hand; HEIGHT: 125px" alt="" src="http://2.bp.blogspot.com/_7rZ3Sa3EABQ/SafejCPY8aI/AAAAAAAAAII/BYH0PJfxhrs/s320/images.jpg" border="0" /></a><br />Rotary kiln with :<br />a – four stage preheater Kilns .<br />Single or twin cyclone stages . The kiln exit gas use to dry raw material up to a moisture content of 8 % .<br />b – One or Two stage preheater kilns .<br />c – Shaft suspension preheater .<br />d – Pre-calciner Kilns .<br />Total fuel used in this system divided to<br />35 % in main burner and 65 % in pre-calciner to achieve > 90 % calcination in pre-heater .<br /><strong><em><span style="color:#ff0000;">Guidelines for choosing kiln systems</span></em></strong><br />1-Production capacity and investment costs .<br />2-Raw material .<br />3-Heat economy .<br />4-Power consumption and pressure drop .<br />5-Operation and maintenance .</div>mostafahttp://www.blogger.com/profile/06263352237762090405noreply@blogger.com0tag:blogger.com,1999:blog-7470594092202111826.post-25932628139803148532009-02-28T10:18:00.001+02:002009-02-28T10:18:01.933+02:00Clinker Microstructure<strong><span style="color:#ff0000;"><em>Clinker Microstructure</em></span></strong><br />The microstructure or fabric of a clinker is also decisive when considering phenomena such as clinker grinding , cement hydration and hardening . <a href="http://1.bp.blogspot.com/_7rZ3Sa3EABQ/Safc3SX-vdI/AAAAAAAAAIA/k977IcCYUmk/s1600-h/images.jpg"><img id="BLOGGER_PHOTO_ID_5307453528262753746" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; WIDTH: 121px; CURSOR: hand; HEIGHT: 121px" alt="" src="http://1.bp.blogspot.com/_7rZ3Sa3EABQ/Safc3SX-vdI/AAAAAAAAAIA/k977IcCYUmk/s320/images.jpg" border="0" /></a><br />Microscopical appearance of clinker phase<br />1 – Alite ( C3S ) .<br />External Form Alite , the principal constituent of cement clinker , occurs as idiomorphic crystals , i.e sharp-edged crystals .<br />2 – Belite ( C2S ) .<br />External Form , round crystal form is the most characteristic shape of belite . <a href="http://3.bp.blogspot.com/_7rZ3Sa3EABQ/SafcdvbvaJI/AAAAAAAAAH4/luoeZBlG9GE/s1600-h/images.jpg"><img id="BLOGGER_PHOTO_ID_5307453089386555538" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; WIDTH: 119px; CURSOR: hand; HEIGHT: 108px" alt="" src="http://3.bp.blogspot.com/_7rZ3Sa3EABQ/SafcdvbvaJI/AAAAAAAAAH4/luoeZBlG9GE/s320/images.jpg" border="0" /></a><br />3 – Free Lime ( F.L ) .<br />Free Lime always appears as rounded spherical crystal .<br />4 – Aluminates .<br />Aluminates appear as cubic form .<br />5 – Ferrite .<br />Like aluminates appears as cubic form .<br />6 – Periclase .<br />Appears as idiomorphic crystal .<br /><strong><em><span style="color:#ff0000;">Influence of production condition on clinker microstructure</span></em></strong><br />The microstructure of industrially product clinker is influenced by several process parameters :<br />a – Raw mix properties :<br />I – Chemical composition .<br />II – Fineness and mineralogy .<br />III – Homogeneity .<br />b – Fuel type .<br />c – Burning conditions :<br />I – Burning time / temperature .<br />II – Kiln atmosphere .<br />d – Cooling condition :<br />I – Rate of cooling .mostafahttp://www.blogger.com/profile/06263352237762090405noreply@blogger.com0tag:blogger.com,1999:blog-7470594092202111826.post-37717139979174907262009-02-24T10:00:00.000+02:002009-02-24T10:00:00.806+02:00Sulphate Resistance Cement – SRC Grade 32.5 RSRC is defined as the hydraulic bonding grey fine powder which is the result from crushing a dry mi<a href="http://2.bp.blogspot.com/_7rZ3Sa3EABQ/SZ_cW4ExtmI/AAAAAAAAAHw/7q9J_He3qLo/s1600-h/clip_image02202.jpg"><img id="BLOGGER_PHOTO_ID_5305201171633387106" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; WIDTH: 127px; CURSOR: hand; HEIGHT: 183px" alt="" src="http://2.bp.blogspot.com/_7rZ3Sa3EABQ/SZ_cW4ExtmI/AAAAAAAAAHw/7q9J_He3qLo/s320/clip_image02202.jpg" border="0" /></a>x made of clinker and gypsum.<br />Adding and mixing water to it harden this grey fine powder, and this is what makes it resistant to water and able to bare compressive stresses, as well as resistant to sulphates that exist in soil, such as clay soil.<br />In this type of cement it is necessary to decrease the ratio C3A less than 3.5%, because this component reacts with Ca SO4, which exists in soil or water. The result of this reaction is called Etringite, which is aproximately 277% of the volume of C3A, and causes cracks that leads to concrete failures.<br />Part of the sulphate resistance cement composition is an adittion of Fe2O3 mixed with row materials. Fe2O3 facilitates the reduction of Etringite and increases C4AF, which does not have the property of expansioning volume; so it has higher resistance against sulphates.<br /><strong><em><span style="color:#ff0000;">Uses and applications:</span></em></strong><br />It can be used in all concrete constructions such as reinforced concrete foundations, sewage drainage tanks, bridge foundations, piles...which are exposed to be directly affected by sulfates.<br />It can also be used in sewage concrete pipes and lining steel pipes.<br /><strong><em><span style="color:#ff0000;">Shelf time:</span></em></strong><br />6 weeks, since the production date.<br /><strong><em><span style="color:#ff0000;">Safety recommendations:</span></em></strong><br />It is recommended to follow the coming instructions:<br />Avoid the contact of the cement with the eyes and the skin since it may cause allergic reaction.<br />Use gloves and glasses to protect hands and eyes in case of spry applications, or manual mixings.<br />It is no poison, according to all international specification for safety and health.<br /><strong><em><span style="color:#ff0000;">Packing:</span></em></strong><br />Bags: 50 Kg/bag<br />Jumbo plastic bags:500 Kg/bag1000 Kg/bag1500 Kg/bag<br />It is also available in bulk<br /><strong><em><span style="color:#ff0000;">Storage:</span></em></strong><br />It is recommended to follow the coming instructions:<br />Storage should be done in a dry place and away from ground moisture.<br />It is preferable to store it on wooden bases.<br />Cement should be covered to avoid the rain.<br />It is recommended not to pile up any more than ten bags, some on others.<br /><strong><em><span style="color:#ff0000;">How to clean the cement remains of the used tools:<br /></span></em></strong>Before setting: by using clean water.<br />After setting: by using mechanical methods.<br /><em><strong><span style="color:#ff0000;">Environment concept</span></strong></em><br />It is advised and recommended to follow local environmental instructions.mostafahttp://www.blogger.com/profile/06263352237762090405noreply@blogger.com3tag:blogger.com,1999:blog-7470594092202111826.post-48371693541816070502009-02-23T10:43:00.001+02:002009-02-23T10:43:00.744+02:00Premium Brand – El Mohandes<a href="http://2.bp.blogspot.com/_7rZ3Sa3EABQ/SZ_bahW-HeI/AAAAAAAAAHo/mFWlFIbeoxw/s1600-h/clip_image0202.jpg"><img id="BLOGGER_PHOTO_ID_5305200134743530978" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; WIDTH: 128px; CURSOR: hand; HEIGHT: 176px" alt="" src="http://2.bp.blogspot.com/_7rZ3Sa3EABQ/SZ_bahW-HeI/AAAAAAAAAHo/mFWlFIbeoxw/s320/clip_image0202.jpg" border="0" /></a> El Mohandes cement is a very special formula of Ordinary Portland cement that gives relatively delayed initial setting time, early compressive strength for concretes, and moderate heat of hydration for concrete and mortar<br />Generally, El Mohandes is recommended for mixing concrete in hot weather and suitable to be used in ready mix concrete plants, factory precast concrete elements, and prefabricated concrete units.<br /><strong><em><font color="#ff0000">Uses and applications:</font></em></strong><br />It can be used in all types of constructions, which need high early compressive strength, such as bridges, tunnels, prefabricated floor, and precast concrete...<br />Advantages:<br />1. It gives relatively high early compressive strength after7 days.<br />2. It gives high final compressive strength (28 days).<br />3. It gives a relatively delayed setting time and reduces the ratio of concrete normal and super plasticisers admixtures (this admixture is used to delay initial setting time of concrete and give more workability).<br /><font color="#ff0000"><strong><em>Shelf time:</em></strong></font><br />3 months, from the production date.<br />It is recommended to retest the cement after 6 weeks.<br /><strong><em><font color="#ff0000">Safety recommendations:<br /></font></em></strong>It is recommended to follow the coming instructions:<br />Avoid the contact of the cement with the eyes and the skin since it may cause allergic reaction.<br />Use gloves and glasses to protect hands and eyes in case of spry applications, or manual mixings.<br /><strong><em><font color="#ff0000">Packing:</font></em></strong><br />Bags: 50 Kg/bag<br />Jumbo plastic bags:500 Kg/bag1000 Kg/bag1500 Kg/bag<br />It is also available in bulk<br /><strong><em><font color="#ff0000">Storage:<br /></font></em></strong>It is recommended to follow the coming instructions:<br />Storage should be done in a dry place and away from ground moisture.<br />It is preferable to store it on wooden bases.<br />Cement should be covered to avoid the rain.<br />It is recommended not to pile up any more than ten bags, some on others.<br /><strong><em><font color="#ff0000">How to clean the cement remains of the used tools:</font></em></strong><br />Before setting: by using clean water.<br />After setting: by using mechanical methods.<br /><strong><em><font color="#ff0000">Environment concept</font></em></strong><br /><div>It is advised and recommended to follow local environmental instructions</div>mostafahttp://www.blogger.com/profile/06263352237762090405noreply@blogger.com1tag:blogger.com,1999:blog-7470594092202111826.post-2556652322168770102009-02-22T10:20:00.000+02:002009-02-22T10:20:01.208+02:00Ordinary Portland Cement – OPCOrdinary Portland Cement was the first cement to be produced all over the world, and the most po<a href="http://1.bp.blogspot.com/_7rZ3Sa3EABQ/SZ_WJFALF8I/AAAAAAAAAHg/pjaBqMn7_1E/s1600-h/clip_image02.jpg"><img id="BLOGGER_PHOTO_ID_5305194337515804610" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; WIDTH: 123px; CURSOR: hand; HEIGHT: 184px" alt="" src="http://1.bp.blogspot.com/_7rZ3Sa3EABQ/SZ_WJFALF8I/AAAAAAAAAHg/pjaBqMn7_1E/s320/clip_image02.jpg" border="0" /></a>pular one.<br />It was named “Portland” because of the similarity in shape and color with the cement material and limestone, which exists in Portland Island, in England.<br />It is defined as the hydraulic bonding grey fine powder which is the result from crushing a dry mix made of clinker and gypsum.<br />Adding and mixing water to it hardens this grey fine powder, which is known as the initial setting, and this is what makes it resistant to water and able to bare compressive stresses.<br /><strong><em><span style="color:#ff0000;">Uses and applications</span></em></strong><br />It can be used in all concrete construction such as reinforced buildings, water tanks, roads, and any other building works, which are not subjected to sulphate effect.<br />It also can be used in relevant industries of the construction, as prefabricated, to produce hollow and solid blocks, tiles and railway line concrete supports.<br /><strong><em><span style="color:#ff0000;">Shelf time</span></em></strong><br />3 months, from the production date.It is recommended to retest the cement after 6 weeks.<br /><strong><em><span style="color:#ff0000;">Safety recommendations</span></em></strong><br />It is recommended to follow the coming instructions:<br />Avoid the contact of the cement with the eyes and the skin since it may cause allergic reaction.<br />Use gloves and glasses to protect hands and eyes in case of spry applications, or manual mixings.<br /><strong><em><span style="color:#ff0000;">Packing:</span></em></strong><br />Bags: 50 Kg/bag<br />Jumbo plastic bags: 500 Kg/bag 1000 Kg/bag 1500 Kg/bag<br />It is also available in bulk.<br /><strong><em><span style="color:#ff0000;">Storage.</span></em></strong><br />It is recommended to follow the coming instructions:<br />Storage should be done in a dry place and away from ground moisture.<br />It is preferable to store it on wooden bases.<br />Cement should be covered to avoid the rain.<br />It is recommended not to pile up any more than ten bags, some on others.<br /><strong><em><span style="color:#ff0000;">How to clean the cement remains of the used tools</span></em></strong><br />Before setting: by using clean water.<br />After setting: by using mechanical methods.<br /><strong><em><span style="color:#ff0000;">Environment concept</span></em></strong><br />It is advised and recommended to follow local environmental instructions.mostafahttp://www.blogger.com/profile/06263352237762090405noreply@blogger.com0tag:blogger.com,1999:blog-7470594092202111826.post-36582668681106320982009-02-21T12:04:00.004+02:002009-02-21T12:20:12.653+02:00Al Fanar Cement<a href="http://2.bp.blogspot.com/_7rZ3Sa3EABQ/SZ_UJkMyRYI/AAAAAAAAAHQ/Y8HsSDjsi5Q/s1600-h/clip_image002.jpg"><img id="BLOGGER_PHOTO_ID_5305192146866947458" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; WIDTH: 129px; CURSOR: hand; HEIGHT: 185px" alt="" src="http://2.bp.blogspot.com/_7rZ3Sa3EABQ/SZ_UJkMyRYI/AAAAAAAAAHQ/Y8HsSDjsi5Q/s320/clip_image002.jpg" border="0" /></a> A type of Portland cement that generates moderate quantity of heat of hydration and moderate sulphates and chloride salts resistance. The scientific concept of Al Fanar Cement is to comply with the standards of Modified Portland Cement Type II by reducing the final total content of Tri-Calcium Aluminates and Tri-Calcium silicate phases as it hydrates generating bigger quantity of heat of hydration.<br /><strong><em><span style="color:#ff0000;">Uses and applications</span></em></strong><br />Generally, Al Fanar Cement is recommended for mixing concrete in the media of double exposure to sulphates and chloride ions such as substructures and superstructures subjected to seawater attack. Also it is suitable for concrete elements of large cross sections (mass concrete).<br /><strong><em><span style="color:#ff0000;">Advantages</span></em></strong><br />1. Moderate heat of hydration that reduces cracks even in mass concrete.<br />2. Balanced moderate Resistance of sulphates and chlorides.<br />3. It gives relatively moderate early compressive strength after7 days.<br />4. It gives high final compressive strength (28 days).<br />5. It gives a relatively delayed setting time and may reduce the needed dosage of concrete admixtures.<br /><strong><span style="color:#ff0000;"><em>Shelf time<br /></em></span></strong>3 months, from the production date. It is recommended to retest the cement after 6 weeks.<br /><strong><em><span style="color:#ff0000;">Safety recommendations</span></em></strong><br />It is recommended to follow the coming instructions:<br />Avoid the contact of the cement with the eyes and the skin since it may cause allergic reaction.<br />Use gloves and glasses to protect hands and eyes in case of spry applications, or manual mixings.<br /><strong><em><span style="color:#ff0000;">Packing</span></em></strong><br />Bags: 50 Kg/bag<br />Jumbo plastic bags:500Kg/bag 1000Kg/bag 1500 Kg/bag<br />It is also available in bulk.<br /><strong><em><span style="color:#ff0000;">Storage</span></em></strong><br />It is recommended to follow the coming instructions:<br />Storage should be done in a dry place and away from ground moisture.<br />It is preferable to store it on wooden ballets.<br />Cement should be covered to avoid the rain.<br />It is recommended not to pile up any more than ten bags, some on others.<br /><strong><em><span style="color:#ff0000;">How to clean the cement remains of the used tools<br /></span></em></strong>Before setting: by using clean water.<br />After setting: by using mechanical methods.<br /><strong><em><span style="color:#ff0000;">Environment concept</span></em></strong><br />Do not dispose of into water or soil so it is advised and recommended to f<a href="http://3.bp.blogspot.com/_7rZ3Sa3EABQ/SZ_UnuqfXSI/AAAAAAAAAHY/t1G2vdSfgbU/s1600-h/clip_image022202.jpg"></a>ollow local environmental instructions.mostafahttp://www.blogger.com/profile/06263352237762090405noreply@blogger.com0tag:blogger.com,1999:blog-7470594092202111826.post-54517268347176213392009-02-19T14:00:00.003+02:002009-02-20T14:22:38.046+02:00Three Main Stages in the Soap Making process<span style="font-size:180%;color:#ff0000;"><strong>1. </strong></span><a name="SAPONIFICATION"><span style="font-size:180%;color:#ff0000;"><strong>SAPONIFICATION</strong></span></a><span style="font-size:180%;color:#ff0000;"><strong> :</strong></span><br /><span style="font-size:180%;color:#ff0000;"></span><br /><br /><a name="The_Batch_Method"><strong><em><span style="color:#ff0000;">The Batch Method</span></em></strong></a><strong><em><span style="color:#ff0000;"><br /></span></em></strong>Semi Boiled Saponification for the production of medium quality soap is made by a simple mixing and heating process in a Crutcher (soap mixer) and is used for making small (1 to 5 tonnes) batches of laundry or household soap. Any impurities in the raw materials will be present in the finished soap and there is no wasted discharge to drain.<br />Fully Boiled Saponification for production of good to high quality soaps is made in kettles. This is the commonest form of soap making. It can be used for laundry soap or toilet soap. The Fully Boiled Soap is washed during the process to remove any impurities or glycerine. Batch size is typically 25 to 50 tonnes and 3 to 5 kettles are used. Typical plant outputs are 1 to 5 tonnes per hour. The fully boiled and washed soap (called neat soap) produces soap to international quality standards. Some wastes may need to be discharged to drain if glycerine is not recovered from these wastes (called lye).<br /><a name="The_Continuous_Process"><strong><em><span style="color:#ff0000;">The Continuous Process</span></em></strong></a><br /><em><span style="color:#ff0000;"><strong>Continuous Saponification</strong></span></em> is suitable for the production of all grades of soap up to the highest quality levels. This system is not suitable for production rates of less than 50 tonnes of soap per day. The system can be sized up to soap production rates in excess of 200 tonnes per day.<br />In the process, raw materials are accurately metered via a special pump to the saponification reactor. Following reaction, the neat soap is separated from the glycerine rich by-product of the reaction. The separation takes place in two main stages, firstly in the rotating disk column, secondly via centrifuge separation. The neat soap is pumped to storage, or directly to vacuum spray drying section.<br />Since glycerine is valuable, the plant will often include a glycerine recovery section to purify the recovered glycerine.<br /><strong><em><span style="color:#ff0000;">Continuous Neutralisation</span></em></strong> is a also a continuous process, but it is significantly simpler than the saponification process. The fatty raw materials in this process are fatty acids rather than palm oil (blends) or tallow.Once again raw materials are accurately metered to a neutralisation reactor. There is no by-product to the neutralisation process, therefore there is no separation stage. The neat soap is pumped to storage, or directly to vacuum spray drying section.<br /><br /><span style="font-size:180%;color:#ff0000;"><strong>2.</strong></span><a name="DRYING_STAGE"><span style="font-size:180%;color:#ff0000;"><strong> DRYING STAGE</strong></span></a><span style="font-size:180%;color:#ff0000;"><strong> :</strong></span><br /><br /><strong><em><span style="color:#ff0000;">Chilling Roll Method<br /></span></em></strong>This process uses chilled rolls to dry the liquid neat soap into soap ribbons. The liquid soap is pumped onto chilled cooling rolls, and immediately solidifies. The solid soap is continuously scraped off the chilling roller as a ribbon or flake and drops into a wooden or plastic tray. When all the trays are full they are placed in racks or trolleys and moved into a Drying Room where they are left for a period to dry or cool.<br /><br /><br /><a name="Vacuum_Spray_Drying_Method"></a><strong><em><span style="color:#ff0000;">Vacuum Spray Drying Method<br /></span></em></strong>The liquid neat soap is pumped through the heat exchanger and then it is sprayed into the v<a href="http://4.bp.blogspot.com/_7rZ3Sa3EABQ/SZv31Bau7xI/AAAAAAAAAHA/2pjB1jCv1Ho/s1600-h/drier.jpg"><img id="BLOGGER_PHOTO_ID_5304105476444581650" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; WIDTH: 231px; CURSOR: hand; HEIGHT: 202px" alt="" src="http://4.bp.blogspot.com/_7rZ3Sa3EABQ/SZv31Bau7xI/AAAAAAAAAHA/2pjB1jCv1Ho/s320/drier.jpg" border="0" /></a>acuum chamber. The water vapour is extracted by a vacuum system and the final water content of the soap is controlled by adjusting the heat exchanger temperature and the level of vacuum. Typical final moisture levels are 22 % moisture for laundry soap and 13 % for toilet soap.<br />The soap dries as it passes across the vacuum chamber and sticks to the internal surfaces. It is scraped off by a set of slowly rotating knives and falls into a plodder on which the vacuum spray chamber is mounted. The plodder continuously extrudes soap whilst maintaining the vacuum seal and can deliver noodles for toilet soap or a continuous extrusion for laundry bars.<br /><br /><br /><span style="font-size:180%;color:#ff0000;"><strong>3. </strong></span><a name="FINISHING"><span style="font-size:180%;color:#ff0000;"><strong>FINISHING</strong></span></a><span style="font-size:180%;color:#ff0000;"><strong> STAGE :</strong></span> <a href="http://4.bp.blogspot.com/_7rZ3Sa3EABQ/SZv3_kboJ9I/AAAAAAAAAHI/252DP3NwppU/s1600-h/hdstamper.jpg"><img id="BLOGGER_PHOTO_ID_5304105657642264530" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; WIDTH: 169px; CURSOR: hand; HEIGHT: 162px" alt="" src="http://4.bp.blogspot.com/_7rZ3Sa3EABQ/SZv3_kboJ9I/AAAAAAAAAHI/252DP3NwppU/s320/hdstamper.jpg" border="0" /></a><br /><br />The finishing process varies whether the final product is Laundry Soap or Toilet Soap. The customer can choose between semi-automatic and fully-automatic levels of operation, both for individual machines or for complete production lines.mostafahttp://www.blogger.com/profile/06263352237762090405noreply@blogger.com0tag:blogger.com,1999:blog-7470594092202111826.post-2664587783465961882009-02-19T08:00:00.001+02:002009-02-19T08:00:00.271+02:00Polypropylene PP<div><br /><br /><div><strong><span style="font-size:130%;color:#ff0000;">Polypropylene PP</span></strong><br /><strong><span style="font-size:130%;color:#ff0000;"></span></strong><br /><strong><em>INTRODUCTION</em></strong><br />Polypropylene (PP) is a linear hydrocarbon polymer, expressed as CnH2n. PP, like polyethylene and polybutene, is a polyolefin or saturated polymer. Polypropylene is one of those most versatile polymers available with applications, both as a plastic and as a fibre, in virtually all of the plastics end-use markets.<br /><strong><em>PROPERTIES</em></strong> <a href="http://4.bp.blogspot.com/_7rZ3Sa3EABQ/SZvzJoVEpWI/AAAAAAAAAGw/MNPCNengsBw/s1600-h/clip_image002.jpg"><img id="BLOGGER_PHOTO_ID_5304100332929066338" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; WIDTH: 330px; CURSOR: hand; HEIGHT: 131px" alt="" src="http://4.bp.blogspot.com/_7rZ3Sa3EABQ/SZvzJoVEpWI/AAAAAAAAAGw/MNPCNengsBw/s320/clip_image002.jpg" border="0" /></a><br />(Semi-rigid, translucent, good chemical resistance, tough, good fatigue resistance, integral hinge property, good heat resistance). Production of polypropylene takes place by slurry, solution or gas phase process, in which the propylene monomer is subjected to heat and pressure in the presence of a <a href="http://2.bp.blogspot.com/_7rZ3Sa3EABQ/SZvziWYbgBI/AAAAAAAAAG4/5H4PytupVBE/s1600-h/clip_image0022.jpg"><img id="BLOGGER_PHOTO_ID_5304100757608038418" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; WIDTH: 320px; CURSOR: hand; HEIGHT: 134px" alt="" src="http://2.bp.blogspot.com/_7rZ3Sa3EABQ/SZvziWYbgBI/AAAAAAAAAG4/5H4PytupVBE/s320/clip_image0022.jpg" border="0" /></a>catalyst system. Polymerisation is achieved at relatively low temperature and pressure and the product yielded is translucent, but readily coloured. Differences in catalyst and production conditions can be used to alter the properties of the plastic. PP does not present stress-cracking problems and offers excellent electrical and chemical resistance at higher temperatures. While the properties of PP are similar to those of Polyethylene, there are specific differences. These include a lower density, higher softening point (PP doesn't melt below 160oC, Polyethylene, a more common plastic, will anneal at around 100oC) and higher rigidity and hardness. Additives are applied to all commercially produced polypropylene resins to protect the polymer during processing and to enhance end-use performance.<br /><strong><em>GRADES AVAILABLE</em></strong> :<br />Three types of polypropylene are currently available. Each suits particular specifications and costing (although there is often some overlap).<br /><strong><em><span style="color:#ff0000;">Homopolymers</span></em> </strong><br />A General Purpose Grade that can be used in a variety of different applications.<br /><strong><em><span style="color:#ff0000;">Block copolymers</span></em></strong><br />incorporating 5-15% ethylene, have much improved impact resistance extending to temperatures below -20oC. Their toughness can be further enhanced by the addition of impact modifiers, traditionally elastomers in a blending process.<br /><strong><em><span style="color:#ff0000;">Random copolymers</span></em></strong><br />incorporate co-monomer units arranged randomly (as distinct from discrete blocks) along the polypropylene long chain molecule. Such polymers typically containing 1-7% ethylene are selected where a lower melting point, more flexibility and enhanced clarity are advantageous.</div></div>mostafahttp://www.blogger.com/profile/06263352237762090405noreply@blogger.com0tag:blogger.com,1999:blog-7470594092202111826.post-43405323949631408692009-02-18T13:27:00.001+02:002009-02-18T13:31:39.636+02:00Applications of polypropylene<strong><span style="color:#ff0000;">Applications of polypropylene<br /></span></strong> Polypropylene can be processed by virtually all thermoplastic-processing methods.<br />Most typically PP Products are manufactured by: extrusion blow moulding, injection moulding.<br /> <strong><em>Flexible Packaging</em></strong><br />PP is one of the leading materials used for film extrusion and has in recent years benefited versus cellophane, metals and paper on account of its superior puncture resistance, low sealing threshold and competitive price.<br /><br /><strong><em>Consumer Products</em></strong><br />Products classified in this sector are Housewares, Furniture, Appliances, Luggage, Toys, Battery Cases and other "durable" items for home, garden or leisure use.<br /> <strong><em>Fibre</em></strong><br />PP Fibre is utilised in a host of applications including tape, strapping, bulk continuous filament, staple fibres, spunbound, and continuous filament.<br /> <strong><em>Industrial</em></strong><br />PP is used to manufacture a range of Sheet, Pipe, Compounding and Returnable Transport Packaging (RTP). With the exception of RTP where Injection Moulding is used, extrusion dominates the conversion process used for these products. Some PP is utilised by the construction sector, most notable domestic drainage pipes.mostafahttp://www.blogger.com/profile/06263352237762090405noreply@blogger.com0tag:blogger.com,1999:blog-7470594092202111826.post-45040001370810393952009-02-15T09:00:00.001+02:002009-02-15T09:00:00.650+02:00Detergents and SoapDetergents and soaps are used for cleaning because pure water can't remove oily, organic soiling. Soap cleans by acting as an emulsifier. Basically, soap allows oil and water to mix so that oily grime can be removed during rinsing. Detergents were developed in response to the shortage of the animal and vegetable fats used to make soap during World War I and World War II. Detergents are primarily surfactants, which could be produced easily from petrochemicals. Surfactants lower the surface tension of water, essentially making it 'wetter' so that it is less likely to stick to itself and more likely to interact with oil and grease.<br />Modern detergents contain more than surfactants. Cleaning products may also contain enzymes to degrade protein-based stains, bleaches to de-color stains and add power to cleaning agents, and blue dyes to counter yellowing.<br />Like soaps, detergents have hydrophobic or water-hating molecular chains and hydrophilic or water-loving components. The hydrophobic hydrocarbons are repelled by water, but are attracted to oil and grease. The hydrophilic end of the same molecule means that one end of the molecule will be attracted to water, while the other side is binding to oil. Neither detergents nor soap accomplish anything except binding to the soil until some mechanical energy or agitation is added into the equation. Swishing the soapy water around allows the soap or detergent to pull the grime away from clothes or dishes and into the larger pool of rinse water. Rinsing washes the detergent and soil away. Warm or hot water melts fats and oils so that it is easier for the soap or detergent to dissolve the soil and pull it away into the rinse water. Detergents are similar to soap, but they are less likely to form films (soap scum) and are not as affected by the presence of minerals in water (hard water).<br /><br /><strong><span style="color:#ff0000;">Petrochemicals/Oleochemicals</span></strong><br />These fats and oils are hydrocarbon chains which are attracted to the oily and greasy grime.<br /><strong><span style="color:#ff0000;">Oxidizers</span></strong><br />Sulfur trioxide, ethylene oxide, and sulfuric acid are among the molecules used to produce the hydrophilic component of surfactants. Oxidizers provide an energy source for chemical reactions. These highly reactive compounds also act as bleaches.<br /><strong><span style="color:#ff0000;">Alkalis</span></strong><br />Sodium and potassium hydroxide are used in detergents even as they are used in soap making. They provide positively charged ions to promote chemical reactions.mostafahttp://www.blogger.com/profile/06263352237762090405noreply@blogger.com0tag:blogger.com,1999:blog-7470594092202111826.post-85845791102890689992009-02-14T13:40:00.000+02:002009-02-14T13:40:00.630+02:00Surfactants<div><br /><br /><div><div><div><div><div><div><div><div><div><br /><div><strong><span style="color:#ff0000;">What is a surfactant?</span></strong><br />A surfactant or surface active agent is a substance that, when dissolved in water, gives a product the ability to remove dirt from surfaces such as the human skin, textiles, and other solids.<br />In more technical terms:<br />(1)they enable the cleaning solution to fully wet the surface being cleaned so that dirt can be readily loosened and removed.<br />(2)they clean greasy, oily, particulate-, protein-, and carbohydrate-based stains.<br />(3)they are instrumental in removing dirt and in keeping them emulsified, suspended, and dispersed so they don't settle back onto the surface being cleaned.<br /><br />Each surfactant molecule has a hydrophilic (water-loving) head that is attracted to water molecules AND a hydrophobic (water-hating) tail that repels water and simultaneously attaches itself to oil and grease in dirt. These opposing forces loosen the dirt and suspend it in the water. The mechanical agitation of the washing machine helps pull the dirt free. Surfactants are one of the major components of cleaning products and can be regarded as the 'workhorses': they do the basic work of breaking up stains and keeping the dirt in the water solution to prevent re-deposition of the dirt onto the surface from which it has just been removed. Surfactants disperse dirt that normally does not dissolve in water. As anyone who uses oil based dressings in the kitchen knows, oil and water do not mix unless shaken vigorously in the bottle. They separate almost immediately afterwards. The same is true when washing your dishes or clothes. With the addition of surfactants, oil, which normally does not dissolve in water, becomes dispersible and can be removed with the wash water.<br /><br /><strong><span style="color:#ff0000;">What does a surfactant actually do?</span></strong><br /><br />Surfactants are also referred to as wetting agents and foamers. Surfactants lower the surface tension of the medium in which it is dissolved. By lowering this interfacial tension between two media or interfaces (e.g. air/water, water/stain, stain/fabric) the surfactant plays a key role in the removal and suspension of dirt. The lower surface tension of the water makes it easier to lift dirt and grease off of dirty dishes, clothes and other surfaces, and help to keep them suspended in the dirty water. The water-loving or hydrophilic head remains in the water and it pulls the stains towards the water, away from the fabric. The surfactant molecules surround the stain particles, break them up and force them away from the surface of the fabric. They then suspend the stain particles in the wash water to remove them.<br /><br /><strong><span style="color:#ff0000;">What does a surfactant "look like"?</span></strong> <a href="http://4.bp.blogspot.com/_7rZ3Sa3EABQ/SZQNG62u8SI/AAAAAAAAAEY/lE6MvRZuKmU/s1600-h/surfactant-appearance.gif"><img id="BLOGGER_PHOTO_ID_5301877073851117858" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; WIDTH: 320px; CURSOR: hand; HEIGHT: 105px" alt="" src="http://4.bp.blogspot.com/_7rZ3Sa3EABQ/SZQNG62u8SI/AAAAAAAAAEY/lE6MvRZuKmU/s320/surfactant-appearance.gif" border="0" /></a><br />A tadpole! A surfactant consists of a hydrophobic (non-polar) hydrocarbon "tail" and a hydrophilic (polar) "head" group. This appearance is key to its behaviour. The dirt-loving or hydrophobic tail absorbs to the oil and grease in dirt and stains.<br /><br /><strong><span style="color:#ff0000;">Are surfactants of natural or synthetic origin ?</span></strong><br />They can be either. Surfactants from natural origin (vegetable or animal) are known as oleo-chemicals and are derived from sources such as palm oil or tallow. Surfactants from synthetic origin are known as petro-chemicals and are derived from petroleum. Having the flexibility to use both oleochemical and petrochemical surfactants allows our formulators to create products that maximize the value in the bottle of detergent, so to speak, by optimizing cleaning ability under a variety of laundry conditions while keeping the price low in the current market. These days, our formulation scientists focus quite a lot on developing detergents that perform well at lower wash temperatures. This approach will continue to yield energy savings during the consumer use phase, hence a reduction of CO2 emissions. Surfactants also have an important role in our body, where they are used to reduce surface tension in the lungs. The human body does not start to produce lung surfactants until late in foetal development. Therefore, premature babies are often unable to breathe properly, a condition called Respiratory Distress Syndrome. Untreated, this is a serious illness and is often fatal, but administration of artificial surfactants virtually eliminates this health problem.<br /><br /><strong><span style="color:#ff0000;">Are there different types of surfactants?<br /></span></strong>There is a broad range of different surfactant types, each with unique properties and characteristics: the type of dirt and fabric on which they work best, how they can cope with water hardness. Detergents use a combination of various surfactants to provide the best possible cleaning results. There are four main types of surfactants used in laundry and cleaning products. Depending on the type of the charge of the head, a surfactant belongs to the anionic, cationic, non-ionic or amphoteric/zwitterionic family. </div><br /><a href="http://3.bp.blogspot.com/_7rZ3Sa3EABQ/SZQOeQ9TkBI/AAAAAAAAAEo/GrspjlTFmZ0/s1600-h/linear-alkyl-sulphate.gif"><img id="BLOGGER_PHOTO_ID_5301878574432882706" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; WIDTH: 320px; CURSOR: hand; HEIGHT: 98px" alt="" src="http://3.bp.blogspot.com/_7rZ3Sa3EABQ/SZQOeQ9TkBI/AAAAAAAAAEo/GrspjlTFmZ0/s320/linear-alkyl-sulphate.gif" border="0" /></a> <div><strong><span style="color:#ff0000;">Anionic surfactants</span></strong></div><br /><div>In solution, the head is negatively charged. This is the most widely used type of surfactant for laundering, dishwashing liquids and shampoos because of its <a href="http://4.bp.blogspot.com/_7rZ3Sa3EABQ/SZQOruA3UdI/AAAAAAAAAEw/NHYoM2sKrOY/s1600-h/branched-alkyl-sulphate.gif"><img id="BLOGGER_PHOTO_ID_5301878805570736594" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; WIDTH: 320px; CURSOR: hand; HEIGHT: 98px" alt="" src="http://4.bp.blogspot.com/_7rZ3Sa3EABQ/SZQOruA3UdI/AAAAAAAAAEw/NHYoM2sKrOY/s320/branched-alkyl-sulphate.gif" border="0" /></a>excellent cleaning properties and high . The surfactant is particularly good at keeping the dirt away from fabrics, and removing residues of fabric softener from fabrics. </div><br /><br /><div><a href="http://1.bp.blogspot.com/_7rZ3Sa3EABQ/SZQPIcThDJI/AAAAAAAAAE4/dwcJ42uETR0/s1600-h/alkyl-ether-sulphates-gif.gif"><img id="BLOGGER_PHOTO_ID_5301879299033336978" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; WIDTH: 320px; CURSOR: hand; HEIGHT: 98px" alt="" src="http://1.bp.blogspot.com/_7rZ3Sa3EABQ/SZQPIcThDJI/AAAAAAAAAE4/dwcJ42uETR0/s320/alkyl-ether-sulphates-gif.gif" border="0" /></a>anionic surfactants are particularly effective at oily soil cleaning and oil/clay soil suspension. Still, they can react in the wash water with the positively charged water hardness ions (calcium and magnesium) , which can lead to partial deactivation. The more calcium and <a href="http://1.bp.blogspot.com/_7rZ3Sa3EABQ/SZQPUzlzsKI/AAAAAAAAAFA/Afjw91pIMQs/s1600-h/fatty-acids-soaps.gif"><img id="BLOGGER_PHOTO_ID_5301879511442501794" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; WIDTH: 320px; CURSOR: hand; HEIGHT: 107px" alt="" src="http://1.bp.blogspot.com/_7rZ3Sa3EABQ/SZQPUzlzsKI/AAAAAAAAAFA/Afjw91pIMQs/s320/fatty-acids-soaps.gif" border="0" /></a>magnesium molecules in the water, the more the anionic surfactant system suffers from deactivation. To prevent this, the anionic surfactants need help from other ingredients such as builders (Ca/Mg sequestrants) and more detergent should be dosed in hard water. The most commonly used anionic surfactants are alkyl sulphates, alkyl ethoxylate sulphates and soaps.<br /><br /><strong><span style="color:#ff0000;">Cationic surfactants</span></strong></div><br /><div>In solution, the head is positively charged. There are 3 different categories of cationics each with their specific application:<br /><br />In fabric softeners and in detergents with built-in fabric softener, cationic surfactant<a href="http://2.bp.blogspot.com/_7rZ3Sa3EABQ/SZQQYvMxr9I/AAAAAAAAAFI/dt9viLIgOr4/s1600-h/esterquat.gif"><img id="BLOGGER_PHOTO_ID_5301880678494875602" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; WIDTH: 320px; CURSOR: hand; HEIGHT: 160px" alt="" src="http://2.bp.blogspot.com/_7rZ3Sa3EABQ/SZQQYvMxr9I/AAAAAAAAAFI/dt9viLIgOr4/s320/esterquat.gif" border="0" /></a>s provide softness. Their main use in laundry products is in rinse added fabric softeners, such as esterquats, one of the most widely used cationic surfactants in rinse added fabric softeners.An example of cationic surfactants is the esterquat.<br /><br /><br />In laundry detergents, cationic surfactants (positive charge) improve the packing of a<a href="http://3.bp.blogspot.com/_7rZ3Sa3EABQ/SZQOESeLNSI/AAAAAAAAAEg/a_cKULLOXeA/s1600-h/4444.gif"><img id="BLOGGER_PHOTO_ID_5301878128162583842" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; WIDTH: 320px; CURSOR: hand; HEIGHT: 94px" alt="" src="http://3.bp.blogspot.com/_7rZ3Sa3EABQ/SZQOESeLNSI/AAAAAAAAAEg/a_cKULLOXeA/s320/4444.gif" border="0" /></a>nionic surfactant molecules (negative charge) at the stain/water interface. This helps to reduce the dirtl/water interfacial tension in a very efficient way, leading to a more robust dirt removal system. They are especially efficient at removing greasy stains. An example of a cationic surfactant used in this category is the mono alkyl quaternary system<br /><strong><span style="color:#ff0000;">Non-ionic surfactants</span></strong></div><br /><div>These surfactants do not have an electrical charge, which makes them resistant to water hardness deactivation. They are excellent grease removers that are used in laundry products, household cleaners and hand dishwashing liquids. Most laundry detergents contain both non-ionic and anionic surfactants as they complement each other's cleaning action. Non-ionic surfactants contribute to making the surfactant system less hardness sensitive. The most commonly used non-ionic surfactants are ethers of fatty alcohols<br /><br /><a href="http://3.bp.blogspot.com/_7rZ3Sa3EABQ/SZQRy-0dTlI/AAAAAAAAAFQ/XCTXRHjJJW0/s1600-h/non-ionic-surfactants.gif"><img id="BLOGGER_PHOTO_ID_5301882228876070482" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; WIDTH: 320px; CURSOR: hand; HEIGHT: 64px" alt="" src="http://3.bp.blogspot.com/_7rZ3Sa3EABQ/SZQRy-0dTlI/AAAAAAAAAFQ/XCTXRHjJJW0/s320/non-ionic-surfactants.gif" border="0" /></a><br /><br /><br />Amphoteric/zwitterionic surfactantsThese surfactants are very mild, making them particularly suited for use in personal care and household cleaning products. They can be anionic (negatively charged), cationic (positively charged) or non-ionic (no charge) in solution, depending on the acidity or pH of the water. They are compatible with all other classes of surfactants and are soluble and effective in the presence of high concentrations of electrolytes, acids and alkalis. These surfactants may contain two charged groups of different sign. Whereas the positive charge is almost always ammonium, the source of the negative charge may vary (carboxylate, sulphate, sulphonate). These<a href="http://1.bp.blogspot.com/_7rZ3Sa3EABQ/SZQSFcv1ndI/AAAAAAAAAFY/PKKfbd66Fsc/s1600-h/alkyl-betaine.gif"><img id="BLOGGER_PHOTO_ID_5301882546147401170" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; WIDTH: 320px; CURSOR: hand; HEIGHT: 93px" alt="" src="http://1.bp.blogspot.com/_7rZ3Sa3EABQ/SZQSFcv1ndI/AAAAAAAAAFY/PKKfbd66Fsc/s320/alkyl-betaine.gif" border="0" /></a> surfactants have excellent dermatological properties. They are frequently used in shampoos and other cosmetic products, and also in hand dishwashing liquids because of their high foaming properties. An example of an amphoteric/zwitterionic surfactant is alkyl betaine.<br /><br /><span style="color:#ff0000;"><strong>How do surfactants work in detail?</strong></span><br />Surfactants can work in three different ways: roll-up, emulsification, and solubilization.</div><br /><div><span style="color:#ff0000;">Roll-up mechanism</span></div><a href="http://1.bp.blogspot.com/_7rZ3Sa3EABQ/SZQS4gpcAqI/AAAAAAAAAFg/S4zKrPmxtfM/s1600-h/roll-up-mechanism-thumb.gif"><img id="BLOGGER_PHOTO_ID_5301883423367627426" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; WIDTH: 112px; CURSOR: hand; HEIGHT: 70px" alt="" src="http://1.bp.blogspot.com/_7rZ3Sa3EABQ/SZQS4gpcAqI/AAAAAAAAAFg/S4zKrPmxtfM/s320/roll-up-mechanism-thumb.gif" border="0" /></a> <div>The surfactant lowers the oil/solution and fabric/solution interfacial tensions and in this way lifts the stain of the fabric.</div><br /><div><span style="color:#ff0000;">Emulsification</span></div><a href="http://4.bp.blogspot.com/_7rZ3Sa3EABQ/SZQTAC0J1bI/AAAAAAAAAFo/csnAX1LMhHY/s1600-h/emulsification-thumb.gif"><img id="BLOGGER_PHOTO_ID_5301883552798463410" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; WIDTH: 112px; CURSOR: hand; HEIGHT: 70px" alt="" src="http://4.bp.blogspot.com/_7rZ3Sa3EABQ/SZQTAC0J1bI/AAAAAAAAAFo/csnAX1LMhHY/s320/emulsification-thumb.gif" border="0" /></a> <div>The surfactant lowers the oil-solution interfacial tension and makes easy emulsification of the oily soils possible. </div><br /><div><span style="color:#ff0000;">Solubilization</span></div><div>Through interaction with the micelles of a surfactant in a solvent (water), a substance spontaneously dissolves to form a stable and clear solution.<br /><br /><strong><span style="color:#ff0000;">How can surfactants prevent dirt from being re-deposited?</span></strong><br />Surfactants have a vital role to play in preventing the re-deposition of soils like greasy, oily stains and particulate dirt on the surface or fabric from which they have just been removed. This works by electrostatic interactions and steric hindrance. </div><div><span style="color:#ff0000;">Electrostatic interactions</span></div><div>Anionic surfactants are adsorbed on both the surface of the dirt which is dispersed in the detergent solution, and the fabric surface. This creates a negative charge on both surfaces, causing electrostatic repulsions. This repulsion prevents the soil from re-depositing on the fabric. In the presence of hardness, however, this mechanism acts like a 'bridge' between the suspended soil and the fabric. This is another reason why hardness sequestrants (a chemical that promotes Ca/Mg sequestration) are often used in detergents. </div><div><span style="color:#ff0000;">Steric hindrance:<br /></span>Non-ionic surfactants like alcohol ethoxylates also adsorb on the dirt. Their long ethoxylated chains extend in the water phase and prevent the dirt droplets or particles from uniting,, and from depositing onto the fabric surface. This is shown in the illustration below: (1) Dirt is present in solution (2) The non-ionic surfactants adsorb to the dirt particles. (3) Their long hydrophilic heads extend in the water phase and as a result prevent the dirt particles/droplets from uniting and from re-depositing onto fabrics. </div></div></div></div></div></div></div></div></div></div></div>mostafahttp://www.blogger.com/profile/06263352237762090405noreply@blogger.com0tag:blogger.com,1999:blog-7470594092202111826.post-25836579719279669802009-02-14T09:01:00.007+02:002009-02-14T09:39:45.126+02:00Petroleum(Oil) A Fossil FuelOil was formed from the remains of animals and plants that lived millions of years ago i<a href="http://1.bp.blogspot.com/_7rZ3Sa3EABQ/SZZsyMVYl5I/AAAAAAAAAGI/YeyaveAm47I/s1600-h/OILGASFORMATION.gif"><img id="BLOGGER_PHOTO_ID_5302545220835514258" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; WIDTH: 309px; CURSOR: hand; HEIGHT: 133px" alt="" src="http://1.bp.blogspot.com/_7rZ3Sa3EABQ/SZZsyMVYl5I/AAAAAAAAAGI/YeyaveAm47I/s320/OILGASFORMATION.gif" border="0" /></a>n a marine (water) environment before the dinosaurs. Over the years, the remains were covered by layers of mud. Heat and pressure from these layers helped the remains turn into what we today call crude oil . The word "petroleum" means "rock oil" or "oil from the earth."<br /><br /><br /><strong><span style="color:#ff0000;">Products Made from a Barrel of Crude Oil</span></strong> (Gallons) <a href="http://1.bp.blogspot.com/_7rZ3Sa3EABQ/SZZwpXcXiZI/AAAAAAAAAGY/3iLw1aDVk9A/s1600-h/barrel.gif"><img id="BLOGGER_PHOTO_ID_5302549467245283730" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; WIDTH: 320px; CURSOR: hand; HEIGHT: 191px" alt="" src="http://1.bp.blogspot.com/_7rZ3Sa3EABQ/SZZwpXcXiZI/AAAAAAAAAGY/3iLw1aDVk9A/s320/barrel.gif" border="0" /></a><br />After crude oil is removed from the ground, it is sent to a refinery by pipeline, ship or barge. At arefinery, different parts of the crude oil are separated into useable petroleum products. Crude oil is measured in barrels (abbreviated "bbls"). A42.U.S gallon of crude oil provides slightly more than 44 gallons of petroleum products. This gain from processing the crude oil is similar to what happens to popcorn, it it gets bigger after it is popped.<br /><a href="http://3.bp.blogspot.com/_7rZ3Sa3EABQ/SZZx0K1ii7I/AAAAAAAAAGo/ECwc03ymcWo/s1600-h/refinery.gif"><img id="BLOGGER_PHOTO_ID_5302550752351390642" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; WIDTH: 352px; CURSOR: hand; HEIGHT: 260px" alt="" src="http://3.bp.blogspot.com/_7rZ3Sa3EABQ/SZZx0K1ii7I/AAAAAAAAAGo/ECwc03ymcWo/s320/refinery.gif" border="0" /></a><br />One barrel of crude oil, when refined, produces about 20 gallons of finished motor gasoline, and 7 gallons of diesel , as well as other petroleum products. Most of the petroleum products are used to produce energy. For instance, many people across the United States use propaneto heat their homes and fuel their cars. Other products made from petroleum include: ink, crayons, bubble gum, dishwashing liquids, deodorant, eyeglasses, records, tires, ammonia, and heart valves.<br /><br /><a href="http://4.bp.blogspot.com/_7rZ3Sa3EABQ/SZZvgdWeP_I/AAAAAAAAAGQ/dkKuyKqy7mA/s1600-h/clip_image002.jpg"></a>mostafahttp://www.blogger.com/profile/06263352237762090405noreply@blogger.com0