Question

$9.2 g N _{2} O _{4}$ is heated in a $1 L$ vessel till equilibrium state is established $N _{2} O _{4}(g) \rightleftharpoons 2 NO _{2}(g)$ In equilibrium state $50 \% N _{2} O _{4}$ was dissociated, equilibrium constant will be (mol. wt. of $N _{2} O _{4}=92$ )

• A. 0.1
• B. 0.4
• C. 0.3
• D. 0.2

Answer 1

Answer: (D)

0.2

Answer 2

$N _{2} O _{4}( g ) \rightleftharpoons 2 NO _{2}( g )$
Molar concentration of
$\left[ N _{2} O _{4}\right]=\frac{9.2}{92}=0.1\, mol / L$
In equilibrium state when it $50 \%$ dissociates,
$\left[ N _{2} O _{4}\right] =0.05\, M$
$\left[ NO _{2}\right] =0.1\, M$
$K_{c} =\frac{\left[ NO _{2}\right]^{2}}{\left[ N _{2} O _{4}\right]}$
$=\frac{0.1 \times 0.1}{0.05}=0.2$