Difference Between Reversible And Irreversible Process In Thermodynamics

What Is Reversible Process?

In thermodynamics, a reversible process is a process whose direction can be returned to its original position by inducing infinitesimal changes to some property of the system via its surroundings. During reversible process, the entropy of the system does not increase and all the changes in state that occur in the system are in thermodynamic equilibrium with each other and the surroundings.

The reversible process can be reversed completely and there is no trace left to show that the system had undergone thermodynamic change.

Important Conditions For The Reversible Reaction To Occur

• The process should occur in infinitesimally small time
• All of the initial and final state of the system should be in equilibrium with each other.

What You Need To Know About Reversible Process

• Reversible processes are those reactions which can be reversed back to the initial state, following the same path that it took to reach the final state, in reverse order.
• Finite changes occur in the system in irreversible processes.
• There is equilibrium between the initial state and the final state of a system where a reversible process has taken place.
• A reversible process can be reversed back to the initial state without making any change in the surrounding environment. 
• Reversible process takes infinite time for completion.
• A reversible process can process in forward or backward direction.
• Work done in a reversible process is maximum i.e larger than the same kind of work done in irreversible process.
• The driving force for the progress of reversible process is significantly small.
• The process happens slowly and through a series of smaller stages.
• The process results in a temporary change.

Examples Of Reversible Process

• Extension of springs
• Slow adiabatic compression or expansion of gases.
• Electrolysis (with no resistance in the electrolyte)
• Frictionless motion of solids
• Slow isothermal compression or expansion of gases.

What Is An Irreversible Process?

In thermodynamic, an irreversible process is defined as a process that cannot be reversed, the process cannot return both the system and the surroundings to their original conditions. During irreversible process, the entropy of the system increases rapidly and it cannot be reduced back to its initial value.

During the irreversible process the various states of the system on the path of change from initial state to final state are not in equilibrium with each other.

There are many factors that make a process irreversible, they include:

• Inelasticity
• Magnetic hysteresis
• Finite temperature difference
• Mixing of two different substances
• Electrical resistance
• Presence of friction and heat losses
• Viscosity

What You Need To Know About Irreversible Process

• Irreversible processes are real-life processes, which cannot be completely reversed back and always accompanied by some loss of heat, work or energy.
• Finite changes in the system in irreversible process.
• During the transformation, there is no equilibrium between the system and surroundings.
• An Irreversible processes cannot be brought back to its initial state without making a change in the surrounding. 
• Irreversible process takes a finite time for completion.
• Irreversible process can only take place in one direction.
• Work done in an irreversible process is always minimum i.e lower than the same work done in a reversible process.
• There is a significant driving force required for the progress of irreversible process.
• The process happens rapidly. 
• The process results in a permanent change.

Examples of irreversible process

• Throttling
• Conduction of heat from a hot body
• Relative motion with friction
• Heat transfer by radiation
• Spontaneous chemical reactions
• Spontaneous mixing of the matter of varying states.
• Diffusion
• Electricity flow through a resistance
• Inelastic deformation
• Magnetization or polarization with a hysteresis
• An explosion

Also Read: Difference Between Physical And Chemical Change

Difference Between Reversible And Irreversible Process In Tabular Form