Question

The equilibrium constant $\left(K_c\right)$ for the reaction $HA+B\rightleftharpoons B{H}^{+}+A^{-}$ is $100$. If the rate constant for the forward reaction is ${10}^5$, then rate constant for the backward reaction is_________.

• A. ${10}^7$
• B. ${10}^3$
• C. ${10}^{-3}$
• D. ${10}^{-5}$

Answer 1

The correct option is B ${10}^3$

$H_A+B\leftrightharpoons B{H}^{+}+A^{-}$

We know

$K_c=\frac{K_f}{K_b}$

$100=\frac{K_f}{K_b}$

$K_b=\frac{{10}^5}{100}$

$K_b={10}^3$

Therefore rate constant for the backward reaction is ${10}^3$

Hence, the correct option is $\text{B}$