Question

The value of $K_c$ for the reaction: $2A\rightleftharpoons B+C$ is $2\times {10}^{-3}$. At a given time the composition of reaction mixture is $\left[A\right]=\left[B\right]=\left[C\right]=3\times {10}^{-4}M$. In which direction the reaction will proceed?

• A. Forward
• B. Backward
• C. At equilibrium
• D. Forward or Backward

Answer 1

Answer: (B)

Backward

For the reaction the reaction quotient $Q_c$ is given by,

$Q_c=\frac{\left[B\right]\left[C\right]}{[A{]}^2}$

as $\left[A\right]=\left[B\right]=\left[C\right]=3\times {10}^{{}_4}M$

$Q_c=\frac{(3\times {10}^{-4})(3\times {10}^{-4})}{(3\times {10}^{-4}{)}^2}=1$

As, $Q_c>K_c$ so the reaction will proceed in the reverse direction