Chapter 5, Problem 5D.2P

(a)

Interpretation Introduction

Interpretation: The labeled phase diagram for the given $\text{P}/\text{S}$ system against $x_{\text{S}}$ has to be drawn and the numerical values of $x_{\text{S}}$ that correspond to the compounds ${\text{P}}_{\text{4}}{\text{S}}_{\text{3}},{\text{P}}_{\text{4}}{\text{S}}_7$ and ${\text{P}}_{\text{4}}{\text{S}}_{\text{10}}$ have to be stated.

Concept introduction: The azeotropic mixture is defined as a mixture of two or more liquids which evaporates without altering the composition of the mixture.  The azeotropic mixture has a constant boiling point because of the same composition in liquid as well as vapor phase.  The components of azeotropic mixture are not separated by distillation processes.

The phase diagram represents the changes in the mixture on changing the conditions like temperature and pressure of the mixture.

(b)

Interpretation Introduction

Interpretation: The cooling curve for a mixture of composition $x_{\text{S}}=0.28$ has to be drawn for the given system when the eutectic exist at $x_{\text{S}}=0.2$.

Concept introduction: The azeotropic mixture is defined as a mixture of two or more liquids which evaporates without altering the composition of the mixture.  The azeotropic mixture has a constant boiling point because of the same composition in liquid as well as vapor phase.  The components of azeotropic mixture are not separated by distillation processes.

The cooling curve is a graphical representation of change of phase of compound.  It is plotted between temperature and time.