Question

What are the types of thermodynamic equilibrium?
A. Thermal equilibrium
B. Mechanical equilibrium
C. Chemical equilibrium
D. All of the above

Answer 1

Thermodynamic equilibrium is the basic concept of thermodynamics. Thermodynamic equilibrium of a thermodynamic system is defined as the system whose properties do not change with time and can only be changed to another condition with the expense of effects on other systems.

Complete answer:
Thermodynamic equilibrium is generally of three types:
Thermal equilibrium: Two systems are said to be in thermal equilibrium when there is no net flow of thermal energy between them and when they are connected by a path permeable to heat. Thermal equilibrium generally follows the zeroth law of thermodynamics. Systems which are in thermodynamic equilibrium are always in thermal equilibrium but converse is not necessarily true in every case.
Mechanical equilibrium: The system is said to be in mechanical equilibrium when there are no unbalanced forces present within the system or between the system and the surrounding. It can also be defined as when the pressure throughout the system, between the system and surrounding is same. But when some unbalanced forces exist within the system then they will get neutralized to attain the condition of equilibrium.
Chemical equilibrium: The system is said to be in chemical equilibrium when there are no chemical reactions going on within the system or we can say there is no transference of matter from one part of the system to another due to diffusion. It is also known that two systems are said to be in chemical equilibrium with each other when their chemical potentials are the same.

Hence option D is the correct answer.

Note:
For the system to be thermodynamic equilibrium it is necessary that it should satisfy the conditions of mechanical, chemical and thermal equilibrium. If any one of the above conditions are not fulfilled then the system is said to be in non-equilibrium.