In: Chemistry
The value of Kc for the reaction:
N2O4(g) ↔ 2NO2 (g)
is 0.21 at 373K. If a reaction vessel at that temperature initially contains 0.030M NO2 and 0.030M N2O4, what are the concentrations of the two gases at equilibrium? First, the reaction quotient (Q) [page 645 of textbook] must be calculated, and then use the I.C.E table [page 648-650 of the textbook] to determine the equilibrium concentrations.
N2O4(g) ↔ 2NO2 (g)
initial 0.03 0.03
change -x +2x
at equlibrium 0.03-x 0.03+2x
Kc = [NO2]2 /[N2O4]
0.21 = (0.03+2x)2/0.03-x
0.0063-0.21x = (0.03)2 + 4x2 + 0.12
4x2 + 0.33x-0.0054 =0
x=0.0139
[N2O4] = 0.03-x
= 0.03-0.0139 = 0.0161M
[NO2] = 0.03+2x
= 0.03+2*0.0139 = 0.0578M