Reversible, Irreversible, Polytropic Process - Practice Questions & MCQ

Reversible or Quasi-Static Process 

It is carried out in such a way that the system remains in a state of equilibrium. All changes occurring at any part of the process will be exactly reversed when the change in carried out in the opposite direction.

• It involves slow changes during operation.

• This process may occur in any direction. 

• Here driving force and opposing force differ with each other by a very small value.

Irreversible Process 

Here the direction of change can not be reversed by small changes in variables. All processes occurring naturally are reversible

• It Involves fast changes during operation.

• It is a unidirectional process. 

• Here, driving and opposing forces differ by a large amount.

Polytropic Process

PV^m = constant is known as general or polytropic process 

If m= 0, the process is constant pressure.

If m = I, the process is isothermal. 

If m =  , the process is adiabatic. 

Thermodynamic Equilibrium 

A system in which the macroscopic properties do not undergo any change with time is called thermodynamic equilibrium. 

If a system is heterogeneous and it is in equilibrium the macroscopic properties in the various phases remain unchanged with time. 

Types: It is of three types-

(i) Mechanical Equilibrium 

Here no mechanical work is done by one of the systems on another part of the system and it is possible if the pressure remains the same throughout the system that is, there is no flow of matter from one part to another 

(ii) Thermal Equilibrium 

There is no flow of heat from one part to another that is, the temperature is constant. 

(iii) Chemical Equilibrium 

There is no change in the composition of any part of the system with time.