Classical thermodynamics, heat transfer Laws of thermodynamics Fact
Clausius statement of the second law
Builds on HeatTemperatureThermodynamic work
Statement
No process can have as its sole result the transfer of heat from a body to a body of higher temperature.
Remarks
"Sole result" is the key phrase. A refrigerator does move heat from a cold body to a hot one, but it needs work from outside, so the transfer is not its only effect. The statement is a form of the second law of thermodynamics and is a law of nature, not a theorem. It is equivalent to the Kelvin–Planck statement: a machine that violates one of them can be combined with an ordinary engine or refrigerator to violate the other. Rudolf Clausius formulated it in the 1850s.
Going deeper
For a student
The Clausius statement is the most direct formulation of the irreversibility of heat flow. With a reversible Carnot cycle it gives Carnot's theorem: no engine between two reservoirs is more efficient than a reversible one. From this one builds the thermodynamic temperature scale, the Clausius theorem and finally the entropy.
Reading path
To understand this page from the ground up, read these 4 pages in order. The foundations come first.
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- Heat concept
- Temperature concept
- Thermodynamic work concept
- Clausius statement of the second law statement
Where this leads
34 pages build on this one.
- Heat engine
- Carnot cycle
- Bridgman's thermodynamic equations
- Fundamental thermodynamic relation
- Clausius theorem
- Carnot's theorem
- Gibbs–Duhem equation
- Entropy production
- Gouy–Stodola theorem
- Szilard engine
- Henry's law
- Local thermodynamic equilibrium
- Euler relation for internal energy
- Rankine cycle
- Principle of minimum energy
- Perpetual motion
- Ehrenfest equations
- Equation of state
- Maxwell equal-area construction
- Ericsson cycle
- Thermodynamic square
- Le Chatelier's principle
- Maxwell's demon
- Ruppeiner geometry
- Maxwell relations
- Contact geometry of thermodynamics
- Kelvin–Planck statement of the second law
- Second law of thermodynamics
- Coefficient of performance
- Principle of maximum entropy in thermodynamics
- Thermal efficiency
- Stirling cycle
- Thermodynamic stability conditions
- Landauer's principle
Further reading
- Web https://en.wikipedia.org/wiki/Second_law_of_thermodynamics, Clausius statement
About this page
| Tag | VECH3HZ04M |
|---|---|
| URI | m2://VECH3HZ04M |
| Kind | statement, fact |
| Writing | W0 stub |
| MSC | 80A05, 80A10 |
| Status | This copy of the site has no build data. Run m2 status VECH3HZ04M. |
| About | Heat |
| Uses | Heat, Temperature, Thermodynamic work |
| Changed | 3 November 2026 |
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