Entropy

Science

Definition

A measure of the disorder or randomness in a system. Nature tends toward increasing entropy, meaning systems naturally move toward more disordered states. Entropy is central to the second law of thermodynamics.

Examples

  • Ice melting into water increases entropy as molecules move more freely
  • A gas expanding to fill an entire room
  • Shuffling a deck of cards increases disorder
Key Fact

ΔS_universe > 0 for all spontaneous processes (Second Law of Thermodynamics)

Related Terms

Enthalpy Gibbs free energy Free energy and equilibrium Phases of matter

Study This Concept

Practice entropy with free review games in these units:

AP Chemistry Unit 6: Thermodynamics