Chapter 19, Problem 91E

Consider the reaction ${\text{X}}_{\text{2}}\left(g\right)\to \text{2 X}\left(g\right)$ . When a vessel initially containing 755 torr of X₂ comes to equilibrium at 298 K, the equilibrium partial pressure of X is 103 torr. The same reaction is repeated with an initial partial pressure of 748 torr of X₂ at 755 K; the equilibrium partial pressure of X is 532 torr. Find $\Delta H°$ for the reaction.