Enthalpy Entropy

Overview

Enthalpy ($H$) and entropy ($S$) are fundamental thermodynamic properties used to analyze energy transfer and process efficiency.

Key Formulas

Enthalpy

$H = U + PV$

Total heat content of a system.

Entropy

$dS = \frac{\delta Q_{rev}}{T}$

Measure of irreversibility.

Gibbs Free Energy

$G = H - TS$

Maximum non-expansion work.

Helmholtz Free Energy

$A = U - TS$

Maximum work at constant volume.

Variables

Symbol	Description	Unit
$H$	Enthalpy	J
$U$	Internal energy	J
$P$	Pressure	Pa
$V$	Volume	m³
$S$	Entropy	J/K
$G$	Gibbs free energy	J
$T$	Temperature	K

Reference Data

References

• Original Source