Equilibrium

Mechanical, thermal, electrostatic, phase and chemical equilibrium

Systems have reached equilibrium when there is no change in the macroscopic state of the systems. Equilibrium of some common systems are described below. Note that the properties describing the state of a system depends on the boundary of the system.

Mechanical Equilibrium

Mechanical systems have reached equilibrium when there is no movement between the systems.

Thermal Equilibrium

Thermodynamic systems have reached equilibrium when there is no heat transfer between the systems. To reach this state of equilibrium the systems must have the same temperature.

Electrostatic Equilibrium

Electrostatic systems have reached equilibrium when there is no net charge flow between the systems.

Phase Equilibrium

Material substance systems have reached equilibrium when there is no net phase transformation, like melting, between the systems.

Chemical Equilibrium

Chemical systems have reached equilibrium when there is no net chemical reaction between the system.