Correct Answer - Option 3 : Internal
Explanation:
Irreversibility:
- A process in which change in the reverse direction does not reverse the process is called Irreversible process and this phenomenon is called Irreversibility.
- In an irreversible process, there is a loss of heat due to radiation, friction, conduction.
- Whenever a process occurs and a substance changes its state from A to B, some of the energy is lost in the universe which cannot be regained. As a result, to bring it back to its original state, some external energy is needed.
- In reality, all the processes are irreversible.
Examples of irreversible processes:
- Heat transfer through a finite temperature difference.
- Friction.
- Plastic deformation.
- The flow of electric current through a resistance.
- Magnetization or polarization with a hysteresis.
- Unrestrained expansion of fluids.
- Spontaneous chemical reactions.
Types of Irreversibility:
- Irreversibility is classified according to their causes:
External irreversibility:
- The irreversibility caused by external physical factors like resistance, viscosity, surface tension, finite temperature difference, external friction.
- The energy lost due to friction can never be regained. Hence, the direction of the process cannot be reversed without supplying external work.
- It is also called Frictional Irreversibility.
Internal irreversibility:
- Irreversibility caused by properties of the working fluid in a process like throttling or free expansion, friction within the system etc.
- When a gas expands, it uses its internal energy to do so. It cannot contract on its own and reverse the process.
Chemical Irreversibility:
- irreversibility caused by internal chemical properties like structure, bonds, etc.
- When a chemical reaction occurs in association with absorption or liberation of heat, it cannot reverse spontaneously.