1  Thermodynamics Quiz

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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.

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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).