For a given reaction, $2 A ightleftharpoons B+C$, the equilibrium constant is $2 \times 10^{-3}$. If at any…
For a given reaction, $2 A ightleftharpoons B+C$, the equilibrium constant is $2 \times 10^{-3}$. If at any given time the composition of the reaction mixture is $[A]=[B]=[C]=6 \times 10^{-5} \mathrm{M}$; predict in which direction the reaction will proceed and the correct value for reaction quotient.
Forward direction and 1.0
Backward direction and 1.0
Forward direction and $3 \times 10^{-5}$
Backward direction and $3 \times 10^{-5}$
Solution
$2 A ightleftharpoons B+C$
Reaction quotient,
$\begin{aligned}
Q & =\frac{[B][C]}{[A]^2}=\frac{\left(6 \times 10^{-5}ight) \times\left(6 \times 10^{-5}ight)}{\left(6 \times 10^{-5}ight)^2} \\
\Rightarrow \quad Q & =1>K_{\mathrm{eq}}=2 \times 10^{-3}
\end{aligned}$
So, the reaction will proceed in backward direction. Given, at an instant,
$[A]=[B]=[C]=6 \times 10^{-5} \mathrm{M}$
and equilibrium constant, $K_{\mathrm{eq}}=2 \times 10^{-3}$