Question

For the reaction $AB(g)\rightleftharpoons A(g)+B(g),AB$ is $33\%$ dissociated at a total pressure of $p$. Therefore, $p$ is related to $K_p$ by one of the following options

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

Answer 1

Answer: (D)

Total pressure at equilibrium,
$=1-0.33+0.33+0.33$
$=1+0.33=1.33$
$p_A=\frac{0.33}{1.33}p$
$p_B=\frac{0.33}{1.33}p$
$p_{AB}=\frac{0.67}{1.33}p$
(Where, $p_A,p_B$ and $p_{AB}$ are partial pressures of $A,B$ and $AB$.)
$K_p=\frac{p_A\cdot p_B}{p_{AB}}$
$=\frac{\frac{0.33}{1.33}p\cdot \frac{0.33}{1.33}p}{\frac{0.67}{1.33}p}$
$=\frac{(0.33{)}^{2}p}{1.33\times 0.67}$
$=\frac{0.1089\times p}{0.8911}$
$K_p=0.122p$
$p=\frac{K_p}{0.122}=8K_p$