Question

Explain, why an organic liquid vaporises at a temperature below its boiling point in its steam distillation?

Answer 1

In steam distillation, the organic liquid starts to boil when the sum of vapour pressure due to the organic liquid (p₁) and the vapour pressure due to water (p₂) becomes equal to atmospheric pressure (p), that is, p = p₁ + p₂

Since p₁ < p₂, organic liquid will vapourise at a lower temperature than its boiling point.