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 $S{O}_{3(g)}$ were found. The equilibrium constant $K_c$ of the reaction would be

• A. 30
• B. 40
• C. 80
• D. 60

Answer 1

Answer: (C)

$\begin{array}{cccccc}& O_2& +& 2S{O}_2& \rightleftharpoons & 2S{O}_3\\ att=0& 1& & 2& & 0\\ atequil.& \left(1-\alpha \right)& & 2\left(1-\alpha \right)& & 2\alpha \end{array}$
Given at equilibrium
$K_c=\frac{{\left(2\alpha \right)}^2}{\left(1-\alpha \right){\left(2-2\alpha \right)}^2}=\frac{\begin{array}{c}2\alpha =1.6\\ \alpha =0.8\\ {\left(0.8\right)}^2\end{array}}{\left(1-0.8\right){\left(1-0.8\right)}^2}$
$=\frac{0.64}{0.002}$
$K_c=80$