JEE Main · ChemistryMedium

$For the reaction PCl_{5} (g) ⇌ PCl_{3} (g) + Cl_{2} (g), the degree of dissociation is α at total pressure P . If the pressure is increased to 4 P, the new degree of dissociation α^{'} will be approximately:$

A. $α /2$
B. $2 α$
C. $α /4$
D. $4 α$

Show correct answer & step-by-step solution

Correct answer: A — $α /2$

Solution

$The equilibrium constant K_{p} is given by K_{p} = \frac{α ^{2} P}{1 - α ^{2}} .$
$For small α, K_{p} \approx α^{2} P, so α \propto \frac{1}{P} .$
$If pressure P becomes 4 P, then α^{'} \propto \frac{1}{4 P} = \frac{1}{2 P} .$
$Therefore, α^{'} = \frac{α}{2} .$
$Hence the answer is (A).$

Attempt this question & track your score

Sign up free to answer, get instant scoring, and let SolveGini track which Chemistry topics you need to revise.

Attempt & Track Free →

More Equilibrium practice questions

View all Equilibrium questions →