A system can achieve Thermodynamic equilibrium in the following two ways.
- When the system is isolated from the surrounding through an adiabatic wall
- When the system has same thermodynamic state as that of surrounding. Such a system is called to be in dead state.
For being in thermodynamic equilibrium, a system has to necessarily achieve following three types of equilibrium.
- Thermal equilibrium
- Mechanical equilibrium
- Chemical equilibrium
Now let us discusses each of the above-mentioned type of equilibrium in detail.
The equilibrium states achieved by two (or more) systems, characterized by restricted values of thermodynamic properties of the systems, after they have been in communication with each other through diathermic wall.
A system is said to be in thermal equilibrium with its surrounding if both have same temperature.
A system is said to be in mechanical equilibrium when there is no work transfer between the system and the surrounding.
A system is said to be in mechanical equilibrium if there is no pressure difference between the system and the surrounding.
A system is said to be in chemical equilibrium if there is no chemical reaction and mass transfer between the system and the surrounding.