Question

Nitrogen and oxygen do not react appreciably at room temperature, as illustrated by our atmosphere. But at high temperatures, the reaction below can proceed to a measurable extent. N2(g) + O2(g) ⇔ 2 NO(g) At 3000 K, the reaction above has Keq = 0.0153. If 0.1852 mol of pure NO is injected into an evacuated 2.0-L container and heated to 3000K, what will be the equilibrium concentration of NO?

Answer 1

   N2(g)      +        O2(g)     <====>        2 NO(g)

initial             0 M                   0 M                               0.1852/2 = 0.0926 M

change         x M                   x M                             2x

equili            x M    x M                          0.0926-2x

Keq = [NO]^2/[N2][O2]

0.0153 = (0.0926-2x)^2/x^2

x = 0.0436 M

at equilibrium

[N2] = x = 0.0436 M , [O2] = 0.0436 M

[NO] = 0.0926-2*0.0436 = 0.0054 M