Question

The reaction N2(g)+O2(g)⇌2NO(g)  is carried out at a temperature at which Kc = 0.050. The reaction mixture starts with only the product, [NO] = 0.0400 M , and no reactants.

Find the equilibrium concentrations of N2 at equilibrium.
Find the equilibrium concentrations of O2 at equilibrium.
Find the equilibrium concentrations of NO at equilibrium.

Answer 1

N2(g) +   O2(g) <------> 2NO(g)
0                0                        0.0400   (initial)
x                 x                        0.0400-2x (at equilibrium)

Kc= [NO]^2 / [N2][O2]
0.050 = (0.0400-2x)^2 / (x)^2
0.2236 = (0.0400-2x)/x
0.2236*x = 0.0400-2x
2.2236*x = 0.0400
x = 0.0180 M

[N2 ] = x = 0.0180 M
[O2 ] = x = 0.0180 M
[NO] = 0.0400-2x = 0.0400-2*0.0180 = 0.0220 M