Question

For the reaction $AB\left(g\right)$$\rightleftharpoons$$A\left(g\right)+B\left(g\right)$, AB is $33\%$ dissociated at a total pressure of P. Therefore P is related to $K_p$ is :

• A. $P=K_p$
• B. $P=3K_p$
• C. $P=4K_p$
• D. $P=8K_p$

Answer 1

Answer: (D)

$P=8K_p$

$AB\left(g\right)\rightleftharpoons A\left(g\right)+B\left(g\right),$

No. of moles initially, $1$ $0$ $0$

No. of moles at equilibrium, $(1-\frac{1}{3})$ $\frac{1}{3}$ $\frac{1}{3}$

Total no. of moles $\frac{2}{3}+\frac{1}{3}+\frac{1}{3}=\frac{4}{3}$

$K_p=\frac{P_A\times P_B}{P_{A}B}$
$P_{AB}=X_{AB}\times P$
$P_A=X_A\times P$
$P_B=X_B\times P$

$K_P=\frac{\left(\frac{1}{3}/\frac{4}{3}\right)P\times \left(\frac{1}{3}/\frac{4}{3}\right)P}{\left(\frac{2}{3}/\frac{4}{3}\right)P}=\frac{1}{8}P$

$P=8K_P$