Question

Pure ammonia is placed in a vessel at a temperature where its dissociation constant is appreciable. At equilibrium:

• A. $\mathrm{Kp}$ does not change significantly with pressure
• B. The degree of dissociation does not change with pressure
• C. the concentration of ${\mathrm{NH}}_3$ does not change with pressure
• D. the concentration of ${\mathrm{H}}_2$ is less than that of ${\mathrm{N}}_2$

Answer 1

The correct option is A

$\mathrm{Kp}$ does not change significantly with pressure

Explanation for Correct answer:

Option (A) $\mathrm{Kp}$ does not change significantly with pressure

• The equilibrium constant won't with the change in concentrations, volume, pressure, presence of the catalyst, etc.
• The equilibrium constant changes only with the change in temperature of the system.
• For an endothermic reaction, the value of the equilibrium constant increases with an increase in temperature and vice versa.
• For an exothermic reaction, the value of the equilibrium constant decreases with an increase in temperature and vice versa.
• Hence correct option

Explanation for incorrect answer:

Option (B) The degree of dissociation does not change with pressure

• The degree of dissociation will change with pressure.
• Hence incorrect option.

Option (C) The concentration of ${\mathrm{NH}}_3$ does not change with pressure

• The concentration of ${\mathrm{NH}}_3$. change with pressure
• Hence incorrect option.

Option (D) The concentration of ${\mathrm{H}}_2$ is less than that of ${\mathrm{N}}_2$

• The concentration of ${\mathrm{H}}_2$ is greater than that of ${\mathrm{N}}_2$
• Hence incorrect option.