Chapter 26, Problem 26.63P

Interpretation Introduction

Interpretation:

One method for the purification of polystyrene samples is to dissolve the polymer in benzene and then add methanol slowly to precipitate solid polystyrene. It is to be explained why polystyrene precipitates under these conditions.

Concept introduction:

The general rule for solubility is “Like dissolves like”, it means polar compounds are soluble in polar solvents and non-polar compounds are soluble in non-polar solvents. Hydrocarbons e.g. alkane are non-polar thus dissolves in the non-polar solvents (e.g. hexane, benzene) and insoluble in polar solvents. Methanol is a polar solvent, benzene is a non-polar solvent and dissolves most of the compounds having an aromatic ring.