1. Net Heat Transfer (Thermal Equilibrium):
During thermal equilibrium, the net heat transfer between the system and its surroundings becomes zero. This means the system is not losing or gaining heat, and its temperature remains constant over time.
2. Net Force and Torque (Mechanical Equilibrium):
When a system reaches mechanical equilibrium, the net force acting on it and the net torque (turning force) around any axis become zero. This implies that the system is not undergoing any acceleration, and it is in a state of rest or uniform motion.
3. Net Mass Transfer (Mass Balance or Material Equilibrium):
If a system is in mass balance or material equilibrium, there is no net change in the system's total mass. This means that the rate at which mass enters the system is equal to the rate at which mass leaves, resulting in a constant total mass over time.
4. Chemical Potential (Chemical Equilibrium):
Chemical equilibrium occurs when the chemical potential of each species in a chemical reaction becomes equal. At this point, the forward and reverse reactions are occurring at the same rate, and the relative concentrations of reactants and products remain constant without any net change.
5. Gibbs Free Energy (Thermodynamic Equilibrium):
Thermodynamic equilibrium is achieved when the Gibbs free energy of a system is minimized. The Gibbs free energy, which represents the maximum amount of work that can be extracted from a system at constant temperature and pressure, reaches its lowest possible value under equilibrium conditions.
