4. Why is it not possible to obtain pure ethanol by fractional distillation? What general name is given to binary mixtures which show deviation from Raoult’s law and whose components cannot be separated by fractional distillation. How many types of such mixtures are there?
Solution : Pure ethanol cannot be obtained by fractional distillation because when the mixture attains a composition of `95.6%` alcohol and `4.4%` water, it becomes an azeotropic mixture. In general, such mixture are called 'azeotropes'.
