Chapter 21, Problem 42A

Interpretation Introduction

Interpretation:

The physical properties used to separate petroleum compounds during fractional distillation needs to be explained.

Concept introduction:

Distillation technique is used to separate the components of mixture, when the volatility of substances of mixture of two or more substances are different.

Answer to Problem 42A

The physical properties used to separate petroleum compounds during fractional distillation is boiling point.

Explanation of Solution

In fractional distillation process, heat is used to separate out the various components present in the mixture of miscible liquids. Since, heat is used in this process so, the boiling point of the components in the mixture play an essential role. The process involves repeated distillations and condensations. The basic principle for this process is that different liquids on heating boils and evaporates at different temperatures thus, the component possessing lower boiling point will boil first and gets converted to vapor.

Hence, the physical properties used to separate petroleum compounds during fractional distillation is boiling point such that the hydrocarbon possessing lower boiling point due to lower molecular weight will distilled off first whereas the hydrocarbon possessing higher boiling point due to higher molecular weight will distilled off last.