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Give commercial preparation of ethanol. State its properties and uses. |
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Answer» Solution :`to` Ethanol is COMMERCIALLY prepared by the fermentation reaction. The oldest method is from sugars. The sugar in molasses, sugarcane or fruits such as grapes is converted to glucose and FRUCTOSE (both have formula `C_(6)H_(12)O_(6)`), in the presence of enzyme invertase. Glucose and fructose undergo fermentation in the presence of another enzyme, zymase which is found in yeast. `C_(12)H_(22)O_(11) + H_(2)O overset("Invertase")to underset("Glucose")(C_(6)H_(12)O_(6)) + underset("Fructose")(C_(6)H_(12)O_(6))` `C_(6)H_(12)O_(6) overset("Zymase")to 2C_(2)H_(5)OH+ 2CO_(2)` In wine making, grapes are the source of sugars and yeast. As grapes ripen, the quantity of sugar increases the yeast grows on the outer skin. When grapes are crushed, sugar and the enzyme come in contact and fermentation starts. Fermentation takes place in anaerobic conditions (absence of air). Carbon dioxide is released during the fermentation. `to` The action of zymase is inhibited once the percentage of alcohol formed exceeds 14 percent. If air gets into fermentation mixture, the oxygen of the air oxidizes ethanol to ethanoic acid which in turn destroys the taste of alcohol drinks. `to` The commercial alcohol is MADE UNFIT for drinking by addition of copper sulphate (to give it colour) and pyridine (a foul-smelling liquid). It is known as alcohol denaturation. Nowadays, ethanol in large quantities is prepared by hydration of ethene. `to` Properties and uses of ethanol : Ethanol is a colourless liquid with boiling point 351 K. `to` It is used as a solvent in paint industry and in the preparation of a few carbon compounds. |
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