For the reaction $2 \mathrm{~A} \rightleftharpoons \mathrm{B}+\mathrm{C}, \mathrm{K}_{\mathrm{C}}=4 \times…
For the reaction $2 \mathrm{~A} \rightleftharpoons \mathrm{B}+\mathrm{C}, \mathrm{K}_{\mathrm{C}}=4 \times 10^{-3}$. At a given time, the composition of reaction mixture is: $[\mathrm{A}]=[\mathrm{B}]=[\mathrm{C}]=2 \times 10^{-3} \mathrm{M}$.
Then, which of the following is correct?
Reaction has a tendency to go in forward direction.
Reaction has a tendency to go in backward direction.
Reaction has gone to completion in forward direction.
Reaction is at equilibrium.
Solution
$2 \mathrm{~A} \rightleftharpoons \mathrm{B}+\mathrm{C}, \mathrm{K}_{\mathrm{C}}=4 \times 10^{-3}$
At a given time $\mathrm{t}, \mathrm{Qc}_{\mathrm{c}}$ is to be calculated and been compared with $\mathrm{K}_{\mathrm{c}}$.
$\begin{aligned}
& \mathrm{Q}_{\mathrm{C}}=\frac{[\mathrm{B}][\mathrm{C}]}{[\mathrm{A}]^2}=\frac{\left(2 \times 10^{-3}\right)\left(2 \times 10^{-3}\right)}{\left(2 \times 10^{-3}\right)^2} \\
& \mathrm{Q}_{\mathrm{C}}=1
\end{aligned}$
As $Q_c \gt K_c$, so reaction has a tendency to move backward.