Absolute alcohol
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Absolute alcohol or dehydrated alcohol is anhydrous pure ethanol, (C2H5OH) containing no more than one percent water.
It is not possible to obtain absolute alcohol by simple fractional distillation, because a mixture containing around 95.5% alcohol and 4.5% water becomes a constant boiling mixture (an azeotropic mixture). To obtain 100% pure alcohol a small quantity of benzene is added to rectified spirit and the mixture is then distilled. Absolute alcohol is obtained in third fraction that distills over at 351.3 K (78.2 °C).
Because a small amount of the benzene used remains in the solution, the product of this process will cause extensive liver damage if consumed.
There is also an absolute alcohol production process by desiccation using glycerine.