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. Then,

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

Answer 1

The correct option is D $P=8K_p$

$\begin{array}{ccccc}AB\left(g\right)& \rightleftharpoons & A\left(g\right)& +& B\left(g\right)\\ 1& & 0& & 0\\ \frac{2}{3}& & \frac{1}{3}& & \frac{1}{3}\end{array}$
$\left(n_{\text{Equilibrium}}\right)=\frac{2}{3}+\frac{1}{3}+\frac{1}{3}=\frac{4}{3}$
$\therefore K_p=\frac{P_A.P_B}{P_{AB}}=\frac{\left(\frac{\frac{1}{3}}{\frac{4}{3}}P\right)\left(\frac{\frac{1}{3}}{\frac{4}{3}}P\right)}{\left(\frac{\frac{2}{3}}{\frac{4}{3}}P\right)}$
or, $K_p=\frac{1}{8}P$
$\Rightarrow P=8K_p$