Question

For the reaction at equilibrium: $N_2{O}_4\left(g\right)\rightleftharpoons 2N{O}_2\left(g\right)$, the concentration of $N_2{O}_4$ and $N{O}_2$ at equilibrium are $4.8\times {10}^{-2}$ and $1.2\times {10}^{-2}$ mol/L respectively. The value of $K_c$ for the reaction is:

• A. $3\times {10}^{-3}M$
• B. $3\times {10}^{3}M$
• C. $3.3\times {10}^{2}M$
• D. $3\times {10}^{-1}M$

Answer 1

The correct option is A $3\times {10}^{-3}M$

The equilibrium reaction is $N_2{O}_4\left(g\right)\rightleftharpoons 2N{O}_2\left(g\right)$.

The expression for the equilibrium constant is $K_c=\frac{[N{O}_2{]}^2}{\left[N_2{O}_4\right]}=\frac{(1.2\times {10}^{-2}{)}^2}{4.8\times {10}^{-2}}=3\times {10}^{-3}M$.