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Currently Playing: Thermodynamics 6e - Heat Capacity and the Third Law V

We conclude our examination of the Third Law of Thermodynamics. First, we find that anharmonic oscillations explain heat capacities above the classical prediction based on quadratic degrees of freedom and harmonic oscillators. Then we see that systems can have non-zero entropy at absolute zero by considering the ground-state degeneracy of an ice crystal. Finally, we sum up the Third Law. The most generally agreed upon formulation is the Unattainability Principle - that no process can reach absolute zero temperature in a finite number of steps and in a finite amount of time.