Question

For a gas reaction, $N_2\left(g\right)+3H_2\left(g\right)\rightleftharpoons 2{NH}_3\left(g\right)$, the partial pressures of $H_2$ and $N_2$ are $0.4$ and $0.8$, and the total pressure is $2.8$ at the equilibrium. What will be the value of $K_p$ if all the concentrations are given in $atm$?

Answer 1

$N_2\left(g\right)+3H_2\left(g\right)\rightleftharpoons 2{NH}_3\left(g\right)$
Partial pressures: $0.8$ $0.4$ $[2.8-(0.8+0.4)=1.6]$
At equilibrium,
Applying the law of mass action,
$K_p=\frac{{\left(p_{{NH}_3}\right)}^2}{\left(p_{N_2}\right){\left(p_{H_2}\right)}^3}=\frac{{1.6}^2}{0.8\times {0.4}^3}=50$