1. The problem statement, all variables and given/known data In an experiment , b mole of hydrogen iodide were put into a sealed vessel under pressure p . At equilibrium, x mole of the hydrogen iodide had dissociated , the reaction being represented by the following equation , Express in terms of b and x of Kp . 2. Relevant equations 2HI(g) <---> H2(g) + I2(g) 3. The attempt at a solution Here is my solution : Reactant: Before experiment : b mole of hydrogen iodide under pressure , p At equilibrium : x mole of hydrogen iodide P(pressure) for hydrogen iodide : [(p/b).(x)]^2 Products: Before experiment : unknown At equilibrium : I conclude that mole ratio of total products is the ( b-x ) mol . Therefore , P(pressure) for gas hyrogen and gas iodine : [(b-x).(p/b)]^2 Answer: Kp = ([(b-x).(p/b)]^2 ) / ([(p/b).(x)]^2) = (b^2) / (b-x)^2 If I am wrong , please guide me .