Question

For the reaction equilibrium, N2O4 (g) 2NO2 (g) the concentrations of N2O4 and NO2 at equilibrium are 4.8 × 10–2 and 1.2 × 10–2mol L–1 respectively. The value of Kc for the reaction is

• A. 3.3 × 102mol L–1
• B. 3 × 10–1mol L–1
• C. 3 × 10–3mol L–1
• D. 3 × 103mol L–1

Answer 1

Answer: (C)

3 × 10–3mol L–1

Answer 2

4.8 × 10–2 mol L–1, = 1.2 × 10–2 mol L–1

$K_{C} = \frac{\left\lbrack NO_{2} \right\rbrack^{2}}{\left\lbrack N_{2}O_{4} \right\rbrack} = \frac{1.2 \times 10^{- 2} \times 1.2 \times 10^{- 3}}{4.8 \times 10^{- 2}}$= 0.3 × 10–2

= 3 × 10–3 mol L–1