Question

In the following equilibrium reaction $2A \rightleftharpoons B + C$, the equilibrium concentrations of $A, B$ and $C$ are $1 \times 10^{-3} M$ $2 \times 10^{-3} M$ and $3 \times 10^{-3}M$ respectively at $300\, K$. The value of $K_c$ for this equilibrium at the same temperature is

• A. $\frac{1}{6}$
• B. $6$
• C. $\frac{1}{36}$
• D. $36$
• E. $\frac{1}{24}$

Answer 1

Answer: (B)

For the reaction,

$2 A \rightleftharpoons B+C$

Equilibrium constant, $K_{c}=\frac{[B][C]}{[A]^{2}}$

Given, $[A]=1 \times 10^{-3} M , \quad[B]=2 \times 10^{-3} M$,

$[C]=3 \times 10^{-3} M$

$\therefore K_{c}=\frac{\left(2 \times 10^{-3}\right)\left(3 \times 10^{-3}\right)}{\left(1 \times 10^{-3}\right)^{2}}=6$