Irreversibility

Definition

Irreversibility in thermodynamics refers to processes that cannot be reversed to restore both the system and surroundings to their original states. Such processes result in an increase in entropy.

5 Must Know Facts For Your Next Test

1. Irreversible processes always increase the total entropy of the system and its surroundings.
2. Examples of irreversible processes include natural phenomena such as heat transfer from hot to cold bodies, friction, and spontaneous chemical reactions.
3. During an irreversible process, some energy is dissipated as waste heat, making it impossible to fully recover the initial state.
4. The Second Law of Thermodynamics states that natural processes are irreversible because they tend towards increased entropy.
5. Reversible processes are idealizations; in reality, all physical processes exhibit some degree of irreversibility.

Review Questions

• Why do irreversible processes lead to an increase in total entropy?
• Provide two examples of irreversible processes and explain why they cannot be reversed.
• How does the Second Law of Thermodynamics relate to irreversibility?

Related terms

Entropy:

A measure of the disorder or randomness in a system. In thermodynamics, it quantifies the amount of energy unavailable for doing work.

Second Law of Thermodynamics:

States that the total entropy of an isolated system can never decrease over time and is constant if all processes are reversible.

Reversible Process:

An idealized process that can be reversed without leaving any net change in either the system or its surroundings. It occurs infinitely slowly so that the system remains in equilibrium at all times.