The units of Gibbs free energy are typically expressed in joules (J) or kilojoules (kJ) in the International System of Units (SI). Gibbs free energy is a thermodynamic potential that measures the maximum reversible work that can be performed by a thermodynamic system at a constant temperature and pressure.
In mathematical terms, Gibbs free energy (G) is defined as:
G = H – TS
where:
- H is the enthalpy (in joules or kilojoules)
- T is the temperature (in kelvin)
- S is the entropy (in joules per kelvin or kilojoules per kelvin)
Since enthalpy (H) is measured in joules or kilojoules, and the product of temperature (T) and entropy (S) also results in joules or kilojoules, the units of Gibbs free energy are consistent with these measurements.
In summary, the units of Gibbs free energy are joules (J) or kilojoules (kJ), depending on the scale of the system being analyzed.