Question

How to separate alcohol and water?

Answer 1

Alcohol and water are two different chemical substances. On mixing them together, they form a homogeneous solution. So, they cannot be simply (easily) separated. They have different boiling points. Hence, they can be separated from a homogeneous mixture because of the difference in their boiling points.

Complete answer:
For the separation of mixture of alcohol and water, a technique is used which is known as “fractional distillation”. This technique is used to separate the mixture of chemicals which have differences in their boiling point.
Therefore, we can say that, fractional distillation is a type of distillation which separates a mixture of substances (homogeneous) into parts or fractions according to their boiling points.
The substance with low boiling point will have high vapor pressure and will be evaporated first before the others. It will be then collected in a vessel after distillation.
Boiling point of water is ${100^o}C$ while the boiling point of alcohol is ${78.5^o}C$ .
So, as we can see, the boiling point of ethanol is less than that of water. When heat will be provided, ethanol will be evaporated first and most of the water will remain in liquid state only at that stage.
Hence, in this way, the homogeneous mixture of alcohol and water are separated through fractional distillation.

Note:
There are many advantages of fractional distillation such as, it is easy to implement, efficient. It is used to produce petrol or gasoline and other valuable natural gases and fuels from crude oil. It has some disadvantages too such as, it is expensive, operational hazards and can contribute to environmental pollution.