or,

(3.51)

Therefore,

(3.52)

If K₁ and K₂ are the equilibrium constants evaluated at temperatures T₁ and T₂ respectively

(3.53)

or,

(3.54)

(3.55)

If ΔH is positive, the reaction is said to be endothermic. If ΔH is negative, the reaction is exothermic.