Thermodynamics
Helmholtz Free Energy
Maximum work extractable at constant T and V. Also denoted A.
Variables
FJ
Helmholtz free energy
Available work at const V,T
UJ
Internal energy
Total internal energy
TK
Temperature
Absolute temperature
SJ/K
Entropy
System entropy
Derivation
F = U - TS. At constant T,V: ΔF = ΔU - TΔS. Minimum F at equilibrium.
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Common questions
What is the Helmholtz Free Energy formula?
Helmholtz Free Energy is written F = U - TS. Maximum work extractable at constant T and V. Also denoted A. It belongs to Thermodynamics, under Entropy.
What are the units in F = U - TS?
In SI units, F is helmholtz free energy, measured in kg·m²/s²; U is internal energy, measured in kg·m²/s²; T is temperature, measured in K; S is entropy, measured in kg·m²/(s²·K).
How is the Helmholtz Free Energy formula derived?
F = U - TS. At constant T,V: ΔF = ΔU - TΔS. Minimum F at equilibrium. The result is F = U - TS.