Chapter 13, Problem 61QP

Interpretation Introduction

Interpretation:

The amount of urea (in grams) required to add in water to prepare a solution having thevapor pressure $2.50\text{ mm Hg}$ less than that of pure waterat $30°\text{C}$ is to be determined.

Concept introduction:

Raoult’s law gives the relationship between the partial vapor pressure of solution and the solvent. This law tells that the partial pressure of the solvent above solution $\left(P_1\right)$ is equivalent to the product of 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 mole of that component to the sum of moles of all the components. The relationship between mole fraction $\left(\chi \right)$ and moles $\left(n\right)$ of the component is as follows:

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