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Chemistry Thermodynamics and Thermochemistry Free Energy and Work Function Single Correct MCQ

Published by: CGP EDU Academic Team

Published on: August 14, 2026

If G = – 177 K cal for

(1) 2 Fe(s) + O 2 (g) Fe 2 O 3 (s) and G = – 19 K cal for

(2) 4 Fe 2 O 3 (s) + Fe(s) 3 Fe 3 O 4 (s)

What is the Gibbs free energy of formation of Fe 3 O 4 (s) ?

+ 229.6 kcal/mol

– 242.3 kcal/mol

– 727 kcal/mol

– 229.6 kcal/mol

Text Solution

Verified by Experts

The correct answer is:

G for 3Fe(s) + 2O 2 (g) Fe 3 O 4 (s) can be obtained by taking

[(2) + 4 × (1)] ×

Hence, we get G f = [– 19 + 4 × (– 177)] × = – 242.3 k cal for 1 mole Fe 3 O 4

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