Practice question · Multiple choice
Thermodynamics sets an arbitrary reference point for internal energy, but assigns an absolute value of zero to entropy. What fundamental distinction explains why absolute zero is fixed for entropy alone?
Hints
- What does the Boltzmann formula evaluate to when exactly one microstate is accessible?
- Why do thermodynamic tables quote absolute values for standard entropy but differences for enthalpy?
Show the answer
A. A single ground state leaves no residual microstate ambiguity
Why
Energy zero-points are arbitrary conventions because only energy differences govern work and heat. In contrast, statistical mechanics ties entropy to microstate count W; when a unique ground state yields W = 1, ln W becomes strictly zero.
Practise The Third Law and Low Temperatures
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More questions on The Third Law and Low Temperatures
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