Question

Calculate the Gibbs free energy for the reaction of conversion of ATP into ADP at 293 Kelvin the change in enthalpy is 19.07 Kcal and the change in entropy is 90 cal per Kelvin.

(a) 7.3 cal

(b) -5.3 Kcal

(c) 7.3 Kcal

(d) -7.3 Kcal

I got this question during an internship interview.

I'm obligated to ask this question of Gibbs Energy Change and Equilibrium in section Thermodynamics of Chemistry – Class 11

Answer 1

Right answer is (d) -7.3 Kcal

To explain: We have ΔG = ΔH – TΔS; by substituting ΔH = 19.07 kcal and ΔS = 90 cal/K, we get ΔG = 19.07 Kcal – 293(90 cal/K) = 19.07 Kcal – 26.37 Kcal = -7300 cal = -7.3 Kcal. The Gibbs free energy change is -7.3 Kcal.