Question

A reaction has an equilibrium constant of 6.5×103 at 298 K. At 764K , the equilibrium constant is 0.44.

Find ΔHorxn for the reaction.,

Answer 1

Van't Hoff equation:
ln (
`(K_(2) )/(K _(1))`) = (-ΔH / R) (
`(1)/(T2)` -
`(1)/(T1)`)
T₁ = 298 K and T₂ 764 K
K₁ = 6.5 x 10³ and K₂ = 0.44
R = 8.314 J / mol . K
ln (
`(0.44)/(6.5 x 10^(3))`) = (
`(-ΔHrx)/(8.314)`) x (
`(1)/(764)` -
`(1)/(298)`) = -38933.85 J/mol