H2 + I2 = 2HI
we express Keq as follows:
Keq = [HI]^2 / [H2] [I2]
Where the terms represents the concentrations of
the substances involved. THe concentrations are as follows:
H2 = 0.763 ( 1 / 18.02) / 3.67 = 0.0115 M
I2 = 96.9 ( 1 / 253.8) / 3.67 = 0.1040 M
HI (at equilibrium) = 90.4 ( 1 / 127.91) / 3.67 = 0.1956 M
By the ICE table, we can calculate the
equilibrium concentrations,
H2 I2 HI
I 0.0115 0.1040 0
C -x -x +2x
-----------------------------------------------------------
E 0.0115-0.0963 0.1040-0.0963 0.1926 ===> x = 0.0963
Keq = (0.1926)^2 / (0.0077) (0.0848)
Keq = 56.81