At a given temperature, the equilibrium constant for the formation of HI from H2 and I2 was found to be 29.9. Calculate the equilibrium constant for the decomposition of HI.

The correct answer is: K'= 0.033.

Explanation:

The formation of HI from H₂ and I₂ is given by:

H₂ + I₂ → 2 HI      K= 29.9

The decomposition of HI is the reverse reaction of the formation of HI:

2 HI → H₂ + I₂     K'

Thus, K' is the equilibrium constant for the reverse reaction of formation of HI. It is calculated as the reciprocal of the equilibrium constant of the forward reaction (K):

K' = 1/K = 1/(29.9)= 0.033

Therefore, the equilibrium constant for the decomposition of HI is K'= 0.033