At a given temperature,0.0664 mol N₂O₄(g)is placed in a 1.00 L flask.After reaching equilibrium,the concentration of NO₂(g)is 6.1 $\times$ 10^-3 M.What is K_c for the reaction below?

Question

Quizplus · Accepted Answer

The balanced equation for the reaction is:

2 N2O5(g) ↔ 4 NO2(g) + O2(g)

If the equilibrium concentration of N2O5 is [N2O5] = 6.1 × 10^−10 M, then the equilibrium concentrations of NO2 and O2 are both 2 × [N2O5] = 1.22 × 10^−9 M (due to the 2:4:1 stoichiometry of the balanced equation).

The equilibrium constant expression for the reaction is:

Kc = [NO2]^4 [O2] / [N2O5]^2

Plugging in the equilibrium concentrations gives:

Kc = (1.22 × 10^−9)^4 (1.22 × 10^−9) / (6.1 × 10^−10)^2

Kc = 5.9 × 10^10

Therefore, the best choice is C.

At a Given Temperature,0 ×\times× 10-3 M ×\times× 10-5 B) 1 ×\times× 10-4 C) 5

At a Given Temperature,0 $\times$ 10^-3 M $\times$ 10^-5
B) 1 $\times$ 10^-4
C) 5