Equimolar concentrations of H and I are heated to equilibrium in a 2 L flask. At equilibrium, the forward and the backward rate constants are found to be equal. NH N NH What percentage of initial concentration of H has reacted at equilibrium ? (KERELA CEE 2008)

2 2 H (g) I (g) 2HI(g) Initial moles 1 1 0 At equilibrium 1 1 2 Molar conc. 1 2 1 2 Hence, 2 2 2 2 4 K (1 ) 1 2 But according to the question, K=1 2 1 1 1 3 So, percent dissociation 100 33.33% 3