Nitrogen dioxide decomposes according to the reaction 2NO₂(g) ⇄ 2NO(g) + O₂(g)
Where K_p = 4.48 × 10⁻¹³ at 25°C. What is the value for K_c?

Question

Nitrogen dioxide decomposes according to the reaction 2NO₂(g) ⇄ 2NO(g) + O₂(g) Where K_p = 4.48 × 10⁻¹³ at 25°C. What is the value for K_c?

Quizplus · Accepted Answer

The equilibrium constant expression for this reaction is:
K = [NO]^2[O2]/[NO2]^2
We can convert this to the given equilibrium constant expression using the relationship:
ΔG° = -RTln(K)
ΔG° = -RTln(4.48 × 10^-13) = 17030 J/mol
ΔG° = -RTln(Kc)
-17030 J/mol = -(8.314 J/mol*K)(298 K)ln(Kc)
ln(Kc) = 2.051
Kc = e^(2.051) = 7.78 × 10^0 = 1.83 × 10^-1^4

Nitrogen Dioxide Decomposes According to the Reaction 2NO2(g) ⇄ 2NO(g)

Nitrogen Dioxide Decomposes According to the Reaction 2NO₂(g) ⇄ 2NO(g)