Gibbs Free Energy, Enthalpy & Entropy
- Enthalpy change (ΔH°) and entropy change (ΔS°) come together in a fundamental thermodynamic concept called the Gibbs free energy (G)
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- The Gibbs free-energy equation is:
ΔG° = ΔH° - TΔS°
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- The units of ΔG° are in kJ mol-1
- The units of ΔH° are in kJ mol-1
- The units of T are in K
- The units of ΔS° are in J K-1 mol-1(and must therefore be converted to kJ K-1 mol-1 by dividing by 1000
- When ΔG° is negative, the reaction is thermodynamically favoured and likely to occur
- When ΔG° is positive, the reaction is not thermodynamically favoured and unlikely to occur