Question

Fractional distillation of liquid air is usually used to separate various gaseous mixtures in air. Explain how to;

1. Remove carbon (IV) oxide. 
2. Remove water. 
3. Obtain nitrogen.

Answer 1

1. Passing air through concentrated sodium hydroxide or potassium hydroxide solution.
2. Cool to −25°C to remove water.
3. Cool to −200°C and carry out fractional distillation to obtain nitrogen gas.