Chemistry unit 11

A sealed vessel initially contains only gaseous D2, which dissociates as D2 ⇌ 2D. At a fixed temperature all gases are ideal. If α is the fraction of original D2 molecules dissociated, equilibrium contains n0(1-α) mol D2 and 2n0α mol D. Total pressure is P, and Kp=p(D)^2/p(D2), using a common pressure unit. The same temperature is maintained when volume changes. No gas escapes.