Question

One mole of $O_{2(g)}$ and two moles of $O_{2(g)}$ were heated in a closed vessel of one-litre capacity at 1098 K. At equilibrium 1.6 moles of $SO_{3(g)}$ were found. The equilibrium constant $K_c$ of the reaction would be

• A. 30
• B. 40
• C. 80
• D. 60

Answer 1

Answer: (C)

$\begin{matrix}&O_{2}&+&2SO_{2}&{\rightleftharpoons}&2SO_{3}\\ at\, t = 0&1&&2&&0\\ at\, equil.&\left(1-\alpha\right)&&2\left(1-\alpha \right)&&2\alpha\end{matrix}$
Given at equilibrium
$K_{c} = \frac{\left(2\alpha\right)^{2}}{\left(1-\alpha \right)\left(2-2\alpha \right)^{2}}= \frac{\begin{matrix}2\alpha = 1.6\\ \alpha = 0.8\\ \left(0.8\right)^{2}\end{matrix}}{\left(1-0.8\right)\left(1-0.8\right)^{2}}$
$= \frac{0.64}{0.002}$
$K_{c} = 80$