Chemistry - Liquid Solution Question with Solution | TestHub

Given, $$\begin{array}{l}{p}^{\circ }=\text{vapour pressure of pure solvent}\\ p=\text{ vapour pressure of solution }\\ n_1=\text{ moles of solute }\\ n_2=\text{ moles of solvent }\end{array}$$ Thus, according to Raoult's law. $$\frac{p^{\circ }-p}{p^{\circ }}=x_1=\frac{n_1}{n_1+n_2}$$ $(x_1=$ mole fraction of solute) or, $1-\frac{p}{p^{\circ }}=\frac{n_1}{n_1+n_2}$ $$\frac{p}{p^{\circ }}=1-\frac{n_1}{n_1+n_2}$$ $\Rightarrow$ $$\begin{array}{c}\frac{n_1+n_2-n_1}{n_1+n_2}\\ \frac{p}{p_{\circ }}=\frac{n_2}{n_1+n_2}\end{array}$$ $\Rightarrow p=p^{\circ }\left(\frac{n_2}{n_1+n_2}\right)$