Question

A reaction at equilibrium involving $2$ mol each of $P{Cl}_5,P{Cl}_3,{Cl}_2$ is maintained at ${250}^{o}C$ and total pressure of $3$ atm. The value of $K_p$ is:

Answer 1

A reaction at equilibrium involving $2$ mol each of $P{Cl}_5,P{Cl}_3,{Cl}_2$ is maintained at ${250}^{o}C$ and total pressure of $3$ atm. The value of $K_p$ is $1$.
Each reactant/product has 2 moles. Thus mole fraction of each reactant/ product is
$\frac{2}{2+2+2}=\frac{1}{3}$
Total pressure is 3 atm.
The partial pressure of each reactant/product is
$\frac{1}{3}\times 3=1$ atm.
$K_p=\frac{P_{PC{l}_3}{P}_{C{l}_2}}{P_{PC{l}_5}}$
$K_p=\frac{1\times 1}{1}$
$K_p=1$