Question

For the reaction,
$AB\left(g\right)\rightleftharpoons A\left(g\right)+B\left(g\right)$,
We start with $1$ mole of AB and $25\%$ of which dissociates at a total pressure of $P$, $P$ is related to $K_p$ as:

• A. $P=K_p$
• B. $P=3K_p$
• C. $P=15K_p$
• D. $P=6K_p$

Answer 1

The correct option is C $P=15K_p$

$AB\left(g\right)\rightleftharpoons A\left(g\right)+B\left(g\right)$
initial: $1$ $0$ $0$
at equillibrium: $1-0.25$ $0.25$ $0.25$
Total number of moles at equilibrium
$=0.75+0.25+0.25$
$=1.25$
$p_{AB}=\frac{0.75}{1.25}\times P;p_A=\frac{0.25}{1.25}\times P;p_B=\frac{0.25}{1.25}\times P$
$\therefore K_P=\frac{p_A\times p_B}{p_{AB}}=\frac{(\frac{0.25}{1.25}{)}^2{P}^2}{\frac{0.75}{1.25}P}$
$\Rightarrow K_p=\frac{1}{15}\times P$
$\Rightarrow P=15K_p$