Chapter 14, Problem 113FP

Interpretation Introduction

(a)

Interpretation:

The approximate temperature at which the steam distillation occurs should be determined.

Concept introduction:

Boiling occurs when the total vapor pressure of two immiscible liquids equals to atmospheric pressure (1 atm). So by steam distillation, organic compounds which are insoluble in water can be extracted in low temperature without decomposition.

Interpretation Introduction

(b)

Interpretation:

Why the proportions of the two liquids condensed from the vapor is independent of the composition of the boiling mixture, as long as both liquids are present in the boiling mixture should be explained.

Concept introduction:

A liquid boils when vapor pressure of the liquid equals to external pressure. Vapor pressure of a liquid at a certain temperature depends on its enthalpy of vaporization, when the enthalpy of vaporization is low; vapor pressure of the liquid at a certain temperature is high, because it needs less energy to escape into vapor phase.

Interpretation Introduction

(c)

Interpretation:

Which of the two liquids, water or Cinnamaldehyde, condenses in the greater quantity by mass should be explained.

Concept introduction:

Boiling point depends on intermolecular forces. Higher the intermolecular forces, higher the boiling point. Hence, a liquid with higher boiling point will have a lower vapor pressure at certain temperature compared to a liquid with lower boiling point. However liquid starts to boil when the vapor pressure of the liquid equals to external pressure.