H2 (g) + I2 (g) 2 HI (g)

Question

If the initial concentrations of H2 and I2 are 1.0 M and the initial concentration of HI is 0.5 M (Kc = 54.3 at 430oC).
(a) Is the reaction at equilibrium?

(b) If not, which way will the reaction proceed?

Answer 1

Let K=[HI]²/([H2][I2])

The given reaction is in equilibrium at 430°C, if K=Kc=54.3

Substitute given concentrations to get
K=[HI]²/([H2][I2])
=0.5²/(1*1)
=0.25 < 54.3
Therefore the reaction is not in equilibrium and will proceed in the forward direction until K=Kc.