Gibbs Free Energy
Maximum non-expansion work at constant T and P. ΔG < 0 for spontaneous processes.
Variables
Derivation
G = H - TS. At constant T,P: ΔG = ΔH - TΔS. Process is spontaneous if ΔG < 0.
Your notes
Check value
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- H = 2 J (Enthalpy)
- T = 3 K (Temperature)
- S = 4 J/K (Entropy)
Result: G = -10 J
Other thermodynamics formulas with the same quantities
- Boltzmann Entropy (Entropy) shares Entropy
- Stefan-Boltzmann Law (Heat & Temperature) shares Temperature
- Work (Isothermal Process) (First Law) shares Temperature
- Internal Energy (Ideal Gas) (First Law) shares Temperature
- Ideal Gas Law (Kinetic Theory) shares Temperature
- Ideal Gas Law (Molecular) (Kinetic Theory) shares Temperature
Where this formula is listed
- Thermodynamics formulas, under Entropy, alongside Entropy Change (Ideal Gas).
- In the thermodynamics list it comes after Boltzmann Entropy and before Helmholtz Free Energy.
- Thermodynamics formula sheet, one of 34 formulas printed with symbol keys and SI units.
- The full formula index, grouped by category and topic.
Common questions
What is the Gibbs Free Energy formula?
Gibbs Free Energy is written G = H − TS. Maximum non-expansion work at constant T and P. ΔG < 0 for spontaneous processes. It belongs to Thermodynamics, under Entropy.
What are the units in G = H − TS?
In SI units, G is gibbs free energy, measured in kg·m²/s²; H is enthalpy, measured in kg·m²/s²; T is temperature, measured in K; S is entropy, measured in kg·m²/(s²·K).
How is the Gibbs Free Energy formula derived?
G = H - TS. At constant T,P: ΔG = ΔH - TΔS. Process is spontaneous if ΔG < 0. The result is G = H − TS.