Spontaneous process

Definition

A spontaneous process is a physical or chemical change that occurs without external intervention. It is driven by a decrease in free energy and an increase in entropy.

5 Must Know Facts For Your Next Test

1. Spontaneous processes can occur at different rates; some are fast (like explosions) and others are slow (like rusting).
2. The spontaneity of a process is determined by the Gibbs free energy change ($\Delta G$), where $\Delta G < 0$ indicates a spontaneous process.
3. Entropy ($S$) often increases in spontaneous processes, contributing to the disorder of the system.
4. Temperature and pressure can influence whether a process is spontaneous.
5. Not all exothermic reactions are spontaneous; endothermic reactions can also be spontaneous if they lead to an overall increase in entropy.

Review Questions

• What determines whether a process is spontaneous in terms of Gibbs free energy?
• Can an endothermic reaction ever be spontaneous? Explain why.
• How do temperature and pressure affect the spontaneity of a process?

Related terms

Gibbs Free Energy:

$G$ represents the maximum reversible work that may be performed by a thermodynamic system at constant temperature and pressure.

Entropy:

$S$ is a measure of the disorder or randomness in a system, often increasing during spontaneous processes.

Exothermic Process: $\Delta H < 0$, indicating that heat is released into the surroundings during the reaction.