Question

The degree of dissociation of $PCl_{5}\left(\right.\alpha \left.\right)$ obeying the equilibrium,

$PCl_{5}\left(\right.g\left.\right)\rightleftharpoons PCl_{3}\left(\right.g\left.\right)+Cl_{2}\left(\right.g\left.\right)$ , is approximately related to the pressure at equilibrium by

• A. $\alpha \propto P$
• B. $\alpha \propto \frac{1}{\sqrt{P}}$
• C. $\alpha \propto \frac{1}{P^{2}}$
• D. $\alpha \propto \frac{1}{P^{4}}$

Answer 1

Answer: (B)

So, $\mathrm{K}_{\mathrm{p}}=\frac{\alpha^2}{(1-\alpha)}\left[\frac{\mathrm{P}}{1+\alpha}\right]=\frac{\alpha^2 \mathrm{P}}{1-\alpha^2}$

or $\alpha =\sqrt{\frac{K_{P}}{P}}$ (if $1-\alpha ^{2}=1$ .)