Gibbs Free Energy Calculator
Calculate Gibbs free energy and determine reaction spontaneity.
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Enter the enthalpy change in joules, the temperature in kelvin, and the entropy change in joules per kelvin. The calculator computes the Gibbs free energy and indicates whether the reaction is spontaneous.
About Gibbs Free Energy
Gibbs free energy, named after Josiah Willard Gibbs, combines enthalpy and entropy into a single quantity that predicts reaction spontaneity at constant temperature and pressure. A negative change in Gibbs free energy means the process can occur spontaneously. This concept is central to chemistry, biochemistry, and materials science, governing chemical equilibrium, phase transitions, and the direction of biological processes.
Frequently Asked Questions
What is Gibbs free energy?
Gibbs free energy (G) is a thermodynamic potential that measures the maximum useful work obtainable from a system at constant temperature and pressure. It equals enthalpy minus temperature times entropy: G = H - TS.
How does Gibbs free energy determine spontaneity?
A reaction is spontaneous when delta G is negative. When delta G is positive, the reaction is non-spontaneous. When delta G is zero, the system is at equilibrium.
What are the units of Gibbs free energy?
Gibbs free energy is measured in joules (J) or kilojoules (kJ). Per mole of substance, it is expressed in kJ/mol.