Chapter 5, Problem 5C.3P

(a)

Interpretation Introduction

Interpretation: The pressure of the mixture of benzene and methylbenzene has to be calculated when the boiling begins.

Concept introduction: The total vapour pressure of two volatile liquids is calculated using the Rault’s law.  Rault’s law states that the vapour pressure of an ideal solution is directly related to the mole fraction of the solvent of the mixture.  This is represented by the formula as,

    $p_{\text{total}}=p_{\text{A}}^{\ast }{x}_{\text{A}}+p_{\text{B}}^{\ast }{x}_{\text{B}}$

(b)

Interpretation Introduction

Interpretation: The composition of the vapour of the mixture of benzene and methylbenzene has to be calculated.

Concept introduction: The total vapour pressure of two volatile liquids is calculated using the Rault’s law.  Rault’s law states that the vapour pressure of an ideal solution is directly related to the mole fraction of the solvent of the mixture.  This is represented by the formula as,

    $p_{\text{total}}=p_{\text{A}}^{\ast }{x}_{\text{A}}+p_{\text{B}}^{\ast }{x}_{\text{B}}$

(c)

Interpretation Introduction

Interpretation: The vapour pressure of the mixture of benzene and methylbenzene when only few drops of liquid remain has to be calculated.

Concept introduction: The total vapour pressure of two volatile liquids is calculated using the Rault’s law.  Rault’s law states that the vapour pressure of an ideal solution is directly related to the mole fraction of the solvent of the mixture.  This is represented by the formula as,

    $p_{\text{total}}=p_{\text{A}}^{\ast }{x}_{\text{A}}+p_{\text{B}}^{\ast }{x}_{\text{B}}$