Gibbs Free Energy - Standard Energy Change of Formation

Standard Energy Change of Formation

The standard Gibbs free energy of formation of a compound is the change of Gibbs free energy that accompanies the formation of 1 mole of that substance from its component elements, at their standard states (the most stable form of the element at 25 degrees Celsius and 100 kilopascals). Its symbol is ΔfG˚.

All elements in their standard states (oxygen gas, graphite, etc.) have 0 standard Gibbs free energy change of formation, as there is no change involved.

ΔrG = ΔrG˚ + RT ln Qr; Qr is the reaction quotient.

At equilibrium, ΔrG = 0 and Qr = K so the equation becomes ΔrG˚ = −RT ln K; K is the equilibrium constant.

Read more about this topic:  Gibbs Free Energy

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