Chapter 13, Problem 68QP

Interpretation Introduction

Interpretation:

The molal concentration of the solution is to be calculated.

Concept introduction:

Raoult’s law gives the relationship between the partial vapor pressure of the solution and the solvent. This law states that the partial pressure of the solvent above solution $\left(P_1\right)$ is equivalent to the product of the mole fraction of the solvent $\left({\chi }_1\right)$ and the partial pressure of the pure solvent $\left(P_1^{°}\right)$. It is expressed as follows:

$P_1={\chi }_1{P}_1^{°}$

Mole fraction of a component is the ratio of the moles of that component to the sum of the moles of all the components. The relationship between mole fraction $\left(\chi \right)$ and moles $\left(n\right)$ of the component is as follows:

${\chi }_1=\frac{n_1}{n_1+n_2+\mathrm{....}}$

The molality of a solution can be determined as follows:

$\text{Molality}=\frac{\text{moles of solute}}{\text{mass of solvent (kg)}}$