question_answer 53)

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

Answer:

Steam distillation is actually distillation under reduced pressure. In steam distillation, the mixture boils when sum of vapour pressure of water and organic liquid becomes equal to the atmospheric pressure \[(P={{P}_{1}}+{{P}_{2}})\]. Since, the vapour pressure of water is appreciably higher than that of organic liquid. Therefore, the organic liquid vaporises at a temperature much lower than its normal boiling point.