Consider this equilibrium: H2 (g) + I2 (g) 2HI (g) Keq = 50.0. What is the Keq value when the reaction rewritten: 2HI (g) H2 (g) + I2 (g) Keq = ?

A - 50.0

B 0.0200

C 25.0

D 50.0

E 0.04

The equilibrium constant is equivalent to the ratio of the concentration of the products in equilibrium to the concentration of the reactants in equilibrium. If the reaction is reversed, then the equilibrium constant will become equivalent to the reciprocal of the equilibrium constant of the original reaction. This is:

Keq = 1/50 = 0.02

The answer is B. 0.02