The chemical reaction that causes chromium to corrode in air is given by

4Cr+3O2→2Cr2O3

in which at 298 K

ΔH∘rxn = - 2256 kJ

ΔS∘rxn = - 549.1 J/K

Part A

What is the standard Gibbs free energy for this reaction? Assume the commonly used standard reference temperature of 298 K.

Express your answer as an integer and include the appropriate units.

161376 kJ

Explanation:

The equation for standard Gibbs energy free energy for a reaction is -

ΔG⁰ = ΔH⁰ - TΔS⁰

The values of ΔH⁰, T and ΔS⁰ are given in the question as

ΔH⁰ = - 2256 kJ

T = 298 K

ΔS⁰ = - 549.1 kJ

So, putting these values in the above equation we get

ΔG⁰ = - 2256 - (-549.1 * 298)

ΔG⁰ = - 2256 + 163631.8 = 161375.8 ≈ 161376 kJ

Thus, the standard Gibbs free energy for the reaction mentioned in the question will be 161376 kJ.