Question

What is the free energy of formation value for Al2O3?

(a) 419 kJ mol^-1

(b) 1045 kJ mol^-1

(c) 1576 kJ mol^-1

(d) 2562 kJ mol^-1

The question was posed to me in quiz.

Question is from Types of Corrosion and Oxidation topic in portion Imperfection in Metal Crystals, Fracture, Corrosion and Oxidation of Engineering Material & Metallurgy

Answer 1

The correct choice is (c) 1576 kJ mol^-1

To elaborate: The free energy of formation of metal oxides is denoted by ΔG and is noted at 25^oC. This value is 1045 kJ mol^-1 for Cr2O3 and 1576 kJ mol^-1 for Al2O3.