Clausius statement of the second law of thermodynamics

Definition

The Clausius statement of the second law of thermodynamics asserts that it is impossible for a self-acting machine, unaided by any external force, to transfer heat from a cooler body to a hotter one. This principle underlines the unidirectional nature of spontaneous heat transfer.

5 Must Know Facts For Your Next Test

1. It emphasizes the directionality of natural processes involving heat flow.
2. The Clausius statement can be mathematically expressed as $\Delta S \geq 0$ for isolated systems.
3. It implies that refrigerators and air conditioners require external work to transfer heat from cold to hot regions.
4. This principle is equivalent to the Kelvin-Planck statement in terms of implications for thermodynamic cycles.
5. Violating this statement would mean creating a perpetual motion machine of the second kind, which is impossible.

Review Questions

• What does the Clausius statement say about the direction of heat transfer?
• How does the Clausius statement relate to refrigeration and air conditioning?
• What would be the consequence if the Clausius statement were violated?

Related terms

Second Law of Thermodynamics:

A fundamental principle stating that total entropy always increases over time for an isolated system.

Kelvin-Planck Statement: An alternative formulation of the second law, asserting that no process can convert all absorbed heat into work without any other effect.

Entropy:

A measure of disorder or randomness in a system, often increasing in natural processes according to the second law.