Question

The degree of dissociation of $N_2{O}_4$ into $N{O}_2$ at 1.5 atmosphere and ${40}^{o}C$ is 0.25. Calculate its $K_p$ at ${40}^{o}C$. Also report degree of dissociation at 10 atmospheric pressure at same temperature :

• A. $K_P=0.2,\alpha \simeq 0.2$
• B. $K_P=0.4,\alpha \simeq 0.1$
• C. $K_P=0.8,\alpha \simeq 0.4$
• D. None of these

Answer 1

The correct option is B $K_P=0.4,\alpha \simeq 0.1$

As given,
$\underset{P_0(1-0.25)}{N_2{O}_4}\rightleftharpoons \underset{0.5P_0}{2N{O}_2}\underset{P_0(1+0.25)=1.5}{-}$
$K_P=\frac{\left[\right[0.5P_0{]}^2}{P_0\left(0.75\right)}{P}_0=\frac{1.5}{1.25}atm$
$=\frac{0.25}{0.75}\times \frac{1.5}{1.25}$

$K_P=0.4$

$\alpha \simeq 0.1$