Gibbs free energy (G)

Definition

Gibbs free energy (G) is a thermodynamic potential that measures the maximum reversible work obtainable from a system at constant temperature and pressure. It is used to predict the direction of chemical reactions.

5 Must Know Facts For Your Next Test

1. The equation for Gibbs free energy is $\Delta G = \Delta H - T \Delta S$, where $\Delta H$ is the change in enthalpy, $T$ is the temperature in Kelvin, and $\Delta S$ is the change in entropy.
2. A negative $\Delta G$ indicates a spontaneous reaction, while a positive $\Delta G$ indicates a non-spontaneous reaction.
3. $\Delta G = 0$ signifies that the system is at equilibrium.
4. Gibbs free energy combines both enthalpy and entropy changes to determine spontaneity under constant temperature and pressure conditions.
5. It is named after Josiah Willard Gibbs, an American scientist who contributed significantly to thermodynamics.

Related terms

Enthalpy (H): A measure of the total heat content of a system, often associated with chemical bonds and phase changes.

Entropy (S): A measure of disorder or randomness in a system, indicating the number of possible states it can occupy.

Spontaneity:

The tendency of a process to occur without external intervention, often indicated by negative Gibbs free energy ($\Delta G < 0$).