If the change in free energy of a system is -899 Jmol‾¹ and the entropy change is 10Jmol‾¹k‾¹ at 250C. Calculate the enthalpy change.

A. +2081 Jmol‾¹
B. -2081 Jmol‾¹
C. -649 Jmol‾¹
D. +649 Jmol‾¹

Correct Answer:

Option A = +2081 Jmol‾¹

Explanation

∆G = ∆H – T∆S
-899 = ∆H – 2980
∆H = -899 + 2980 = + 2081 Jmol-1