Question

$\alpha ={\left[K_p/(P+K_p)\right]}^{1/2}$ for $PC{l}_5\rightleftharpoons PC{l}_3+C{l}_2$; where, $\alpha$ is degree of dissociation at temperature when equilibrium constant is .

• A. $K_p$
• B. $K_c$
• C. $2K_p$
• D. $(K_p{)}^2$

Answer 1

The correct option is A $K_p$

Let the initial pressure of $PC{l}_5$ be P atm
The equilibrium pressures of $PC{l}_5,PC{l}_{3}andC{l}_2$ are $P(1-\alpha ),\alpha P,\alpha P$
The expression for the equilibrium constant is $K_p=\frac{P_{PC{l}_3}{P}_{C{l}_2}}{P_{PC{L}_5}}=\frac{\alpha P\alpha P}{P(1-\alpha )}$
Hence, $\alpha ={\left[K_p/(P+K_p)\right]}^{1/2}$