Chemistry - Chemical Equilibrium Question with Solution | TestHub

The relation between $K_p$ and $K_c$ is given by $K_p=K_c(RT{)}^{\Delta n_g}$, where $\Delta n_g$ is the difference between the number of moles of gaseous products and gaseous reactants.

For $K_p\ne K_c$, $\Delta n_g$ must be non-zero.

For ${\text{H}}_2\text{O (g)}+\text{CO (g)}\rightleftharpoons {\text{H}}_2\text{(g)}+{\text{CO}}_2\text{(g)}$, $\Delta n_g=2-2=0\Rightarrow K_p=K_c$

For ${\text{N}}_2\text{(g)}+3{\text{H}}_2\text{(g)}\rightleftharpoons 2{\text{NH}}_3\text{(g)}$, $\Delta n_g=2-4=-2\Rightarrow K_p\ne K_c$

For ${\text{H}}_2\text{(g)}+{\text{I}}_2\text{(g)}\rightleftharpoons 2\text{HI (g)}$, $\Delta n_g=2-2=0\Rightarrow K_p=K_c$

For ${\text{N}}_2\text{(g)}+{\text{O}}_2\text{(g)}\rightleftharpoons 2\text{NO (g)}$, $\Delta n_g=2-2=0\Rightarrow K_p=K_c$

Answer: ${\text{N}}_2\text{(g)}+3{\text{H}}_2\text{(g)}\rightleftharpoons 2{\text{NH}}_3\text{(g)}$