Question

The equilibrium constant K for the reaction $2HI\left(g\right)\rightleftharpoons H_2\left(g\right)+I_2\left(g\right)$ at room temperature is $2.85$ and that at $698K$ is $1.4\times {10}^{-2}$. This implies :

• A. $HI$ is exothermic compound
• B. $HI$ is very stable at room temperature
• C. $HI$ is relatively less stable than $H_2$ and $I_2$
• D. $HI$ is resonance stabilised

Answer 1

The correct option is C $HI$ is relatively less stable than $H_2$ and $I_2$

With the increase in temperature, K value decreases, which. means that at high temperature the reaction proceeds in a backward direction or proceeds forward at room temperature. In other word, at room temperature, HI dissociates or $HI$ is less stable than $H_2$ and $I_2$.