Ethanol Production
Distillation is the purification of gases or liquids by taking advantage of their boiling point differences. Ethanol and water have a fairly large difference in boiling point, but only up to a certain concentration. At 1 atmosphere and about 95 volume % ethanol, the boiling point of this mixture has a boiling point less than either of the pure components and is known to be a minimum boiling azeotrope. The earliest known distillation was between ethanol and water. For millennia, man has made spirits, or "strong drink", from the fermentation of various sugars and starches. These early distillations were typically a single stage, or more simply a pot boiling and a condenser to capture the vapors. This single stage would yield an alcohol content of 40 volume % ethanol (or 80 proof), hence your typical whiskey or brandy. If done twice you can improve the ethanol content further to 70 volume % ethanol, which is your typical cognac before aging. For fuels ethano...