Calculate $K_p$ for the equilibrium,
$ \mathrm{NH}_4 \mathrm{HS}_{(s)} \rightleftharpoons \mathrm{N

Question

Calculate $K_p$ for the equilibrium, 
$ \mathrm{NH}_4 \mathrm{HS}_{(s)} \rightleftharpoons \mathrm{NH}_{3(g)}+\mathrm{H}_2 \mathrm{~S}_{(g)} $
if the total pressure inside the reaction vessel is 1.12 atm at $105^{\circ} \mathrm{C}$.

Professor PC Thomas Classes · Answer

(c) Total gaseous moles at equilibrium $=x+x=2 x$
We know, $K_p=p_{\mathrm{NH}_3} 	imes p_{\mathrm{H}_2 \mathrm{~S}}$
But, partial pressure $(p)=$ mole fraction × total pressure $(P)$
$
K_p=\left(\frac{x}{2 x} 	imes Pight)\left(\frac{x}{2 x} 	imes Pight)=\left(\frac{P}{2}ight)^2=\left(\frac{1.12}{2}ight)^2=0.3136
$