Standard free energy changes, ΔG°

Definition

Standard free energy change, $\Delta G^\circ$, is the change in Gibbs free energy for a reaction under standard conditions (1 bar, 298 K, and 1 M concentration). It indicates whether a reaction is spontaneous under these conditions.

5 Must Know Facts For Your Next Test

1. $\Delta G^\circ$ can be calculated using the equation $\Delta G^\circ = \Delta H^\circ - T\Delta S^\circ$ where $\Delta H^\circ$ is the standard enthalpy change and $\Delta S^\circ$ is the standard entropy change.
2. A negative $\Delta G^\circ$ indicates a spontaneous reaction under standard conditions, while a positive $\Delta G^\circ$ indicates a non-spontaneous reaction.
3. $\Delta G^\circ$ is related to the equilibrium constant $K$ by the equation $\Delta G^\circ = -RT\ln K$, where $R$ is the gas constant and $T$ is the temperature in Kelvin.
4. The value of $\Delta G^\circ$ can predict the direction of a chemical reaction but does not provide information about the rate of the reaction.
5. If $\Delta G^\circ = 0$, it means that the system is at equilibrium under standard conditions.

Related terms

Gibbs Free Energy:

A thermodynamic potential that measures the maximum reversible work obtainable from a system at constant temperature and pressure.

Enthalpy ($\Delta H)$: The measure of total heat content in a thermodynamic system. It reflects both internal energy and work done by or against atmospheric pressure.

Entropy ($\Delta S)$: A measure of disorder or randomness in a system. Entropy changes indicate how much energy has dispersed during a process.