Question: how to calculate keq for a reaction?
Answer: Keq is a numerical value that is dependent on the stoichiometry coefficients. Thus, the chemical equation that Keq refers to must be defined. For example: Rxn 1: H2 + I2 = 2HI Keq = [HI]2/[H2][I2]. Rxn2: 2H2 + 2I2 = 4HI Keq = [HI]4/[H2]2[I2]2.