Gibbs

Definition

Gibbs free energy is a thermodynamic potential that measures the maximum reversible work obtainable from a system at constant temperature and pressure. It indicates the spontaneity of a process; negative values denote spontaneous reactions.

5 Must Know Facts For Your Next Test

1. Gibbs free energy ($G$) is defined by the equation $G = H - TS$, where $H$ is enthalpy, $T$ is temperature, and $S$ is entropy.
2. A negative change in Gibbs free energy ($\Delta G < 0$) indicates a spontaneous process.
3. At equilibrium, the change in Gibbs free energy ($\Delta G$) is zero.
4. The standard Gibbs free energy change ($\Delta G^\circ$) can be related to the equilibrium constant ($K$) by the equation $\Delta G^\circ = -RT \ln K$, where $R$ is the gas constant and $T$ is temperature in Kelvin.
5. Gibbs free energy helps predict whether reactions will proceed without external input under given conditions.

Review Questions

• What does a negative value of Gibbs free energy indicate about a reaction?
• How is Gibbs free energy related to enthalpy, entropy, and temperature?
• What does it mean for a reaction when its change in Gibbs free energy equals zero?

Related terms

Enthalpy: A measure of the total heat content in a system, represented as \(H\).

Entropy: A measure of disorder or randomness in a system, represented as \(S\).

Equilibrium Constant: A dimensionless value denoted by \(K\), which expresses the ratio of product concentrations to reactant concentrations at equilibrium.