Question

For a reaction $H _{2}+ I _{2} \rightleftharpoons 2 HI$ at $721\, K$, the value of equilibrium constant is $50$. If $0.5$ moles each of $H_{2}$ and $I_{2}$ is added to the system, the value of equilibrium constant will be:

• A. 40
• B. 60
• C. 50
• D. 30

Answer 1

Answer: (C)

50

Answer 2

The equilibrium reaction is $H _{2}( g )+ I _{2}( g ) \rightarrow 2 HI ( g )$. The relationship between $Kp$ and $Kc$ is $Kp = Kc ( RT )^{\Delta n }$. For the equilibrium reaction, $\Delta n =2-(1+1)=0$. Hence, $Kp = Kc =50$.