Chemical Forums
Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: ilya559 on May 17, 2004, 09:18:44 PM
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What is needed to distil in order to create a pure ethanol?
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Normal distillation does not work as water and ethanol form a constant boiling mixture, an azeotrope, at 95% ethanol. This means that when your solution is at 95% ethanol, it will boil off as 95% ethanol and not as pure alcohol. In order to get pure ethanol, manufacturers will generally add benzene to the mixture as benzene, ethanol and water form a different azeotrope which will allow the ethanol to be concentrated even further. Drying agents are also added which will absorb any remaining water in the solution. However, traces of Benzene and the other drying agents will remain in the ethanol making it INCREDIBLY bad to ingest. You should never ingest laboratory ethanol as other chemicals like benzene, methanol, acetaldehyde, etc. etc. are added as denaturants. If you want "pure" ethanol, just go to a liquor store and buy a bottle of grain alcohol. That's just 190 proof liquor which has no denaturants added to it. ;D (And it hurts like hell if you do ingest it. lol).
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Ethanol azeotropes with water, you need to dry w 4A molecular seives, distillation alone will not succeed in drying ethanol.