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1  Thermodynamics Quiz

Instructions: Mark each item T or N.
• Mark it T if the statement is reliably true ... with trivial exceptions if any. (If you aren’t sure whether an exception is “trivial” or not, explain briefly.)
• Mark it N if the statement is not reliably true. This includes statements that are sometimes true but sometimes false.

You may assume constant N. You may assume any external applied fields are negligible.

1. T  / N —  Energy is best defined as the ability to do work.

2. T  / N —  dE = dQ + dW. (First law of thermodynamics.)

3. T  / N —  Entropy is best defined via dS := dQ / T.

4. T  / N —  Entropy goes to zero as T goes to zero. (Third law.)

5. T  / N —  Entropy quantifies the amount of disorder in the system.

6. T  / N —  Thermal energy is the random kinetic energy of the particles that make up the system.

7. T  / N —  Heat is best defined as the transfer of energy from one body to another as the result of a difference in temperature.

8. T  / N —  dE is best though of as an infinitesimal step in the direction parallel to the E axis.

9. T  / N —  Heat capacity measures the slope of the curve: heat (energy) added versus temperature.

10. T  / N —  Consider the chemical reaction A ↔ B.
At t=0 we have 50% A and 50% B in equilibrium at temperature T and pressure P. At t=0 we perturb the system by adding a small amount of extra A at the same temperature and pressure. At t=0+ the reaction will proceed to the right, moving back toward 50/50. (Le Châtelier’s «principle».)

11. T  / N —  The internal energy of a given system is naturally a function of (V,S) whereas the enthalpy is naturally a function of (P,S).
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