Thermodynamics
Gibbs Free Energy
Maximum non-expansion work at constant T and P. ΔG < 0 for spontaneous processes.
Variables
GJ
Gibbs free energy
Available work at const P,T
HJ
Enthalpy
H = U + PV
TK
Temperature
Absolute temperature
SJ/K
Entropy
System entropy
Derivation
G = H - TS. At constant T,P: ΔG = ΔH - TΔS. Process is spontaneous if ΔG < 0.
Your notes
0/5000
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.