The reaction,

Cr2O3 + 2 Al → Al2 O3 + 2 Cr (ΔG0 = – 421 kJ)


is thermodynamically feasible as is apparent from the Gibbs energy value.


Why does it not take place at room temperature?

The reaction,


Cr2O3 + 2 Al → Al2 O3 + 2 Cr (ΔG0 = – 421 kJ)


Is thermodynamically feasible as is apparent from Gibbs energy value. The change in Gibbs free energy is related to the equilibrium constant, k as


ΔG = - RT ln K


A certain amount of energy activation is required even for such reactions which are thermodynamically feasible, therefore heating is required.


ΔG = ΔH + S


Increasing the temperature increases the value of TΔS, making the value of ΔG more and more negative. Therefore, the reaction becomes more and more feasible as the temperature is increased.


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