09-214 Physical Chemistry Name_______KEY______________

Quiz 2 February 11, 2000

Closed book. No equations in calculators. Show all work.

For the following process, determine whether each of the thermodynamic quantitites listed is greater than, equal to, or less than zero for the system described. Consider the gas to behave ideally. Indicate your reasoning and state explicitly any reasonable assumptions or approximations that you need to make. (There may not be any.)

A sample of gas is carried through a complete Carnot cycle (isothermal expansion, adiabatic expansion, isothermal compression, adiabatic compression — all reversible): T, q, w, E, H, S, G.

E, H, S, G and T all equal zero because E, H, S, G and T are state functions (state variables) and the full cycle brings them back to their original values (regardless of path).

q is non-zero in both the isothermal expansion and compression. The former input is larger than the latter output and therefore, for the cycle, q > 0. Since E = 0, it's easy to conclude that w < 0.