1. Thermodynamics is the study of the fundamental laws involving heat and work.

2. The system is the group of objects involved in a particular heat-work situation. Everything else makes up the surroundings.

3. Walls that permit heat to pass through them are diathermal walls
Walls that permit heat to pass through them are diathermal walls. Walls that do not permit the flow of heat are adiabatic walls.

4. Two systems are in thermal equilibrium if there is no net flow of heat between them when they are in thermal contact; in other words, they are the same temperature.

5. The zeroth law of thermodynamics - Two systems individually in equilibrium with a third system are in thermal equilibrium with each other.

6. Temperature is the indicator of thermal equilibrium, and there is no flow of heat within a system in thermal equilibrium.

7. The first law of thermodynamics The internal energy of a system changes from an initial value Ui to a final value of Uf due to heat Q and work W: ∆U = Uf - Ui = Q + W .

8. Q is positive when the system gains heat and negative when it loses heat. W is negative when work is done by the system and positive when work is done on the system.

9. The sign of W is opposite the way it is expressed in your text, but this is the way the signs are handled on the AP test.

10. It was changed in 2002, so that energy added to a system and work done on a system are both positive. Energy given off by a system and work done by a system are both negative.

11. Ex 1 - In situation A, a system gains 1500 J of heat from its surroundings, and 2200 J of work is done by the system on the surroundings. In part B, the system also gains 1500 J of heat, but 2200 J of work is done on the system by the surroundings. In each case determine the change in the internal energy of the system.

12. Ex 2 - The temperature of three moles of a monatomic ideal gas is reduced from Ti = 540 K to Tf = 350 K by two different methods. In the first method 5500 J of heat flows into the gas, while in the second method, 1500 J of heat flows into it. In each case find (a) the change in the internal energy of the gas and (b) the work done by the gas.

13. ∆U in the previous problem is calculated to be -7100 J
∆U in the previous problem is calculated to be J. From ∆U = Q + W, W = ∆U - Q. So the first solution is W = = The second is W = = This solution differs from the book solution because we changed the way W is expressed.

14. “An isobaric process is one that occurs at constant pressure
“An isobaric process is one that occurs at constant pressure. In an isobaric process, W = P∆V = P(Vf - Vi). W is still negative for work done by a system (Vf >Vi), and W is positive when work is done on a system (Vf<Vi).”

15. Ex 3 - One gram of water is placed in a cylinder with a movable piston and the pressure is maintained at 2.0 x 10 5 Pa. The temperature of the water is raised by 31°C. In one case, the water is in the liquid phase and expands by the small amount x m3. In another case, the water is in the gas phase and expands by the much greater amount of 7.1 x m3. For the water in each case, find (a) the work done and (b) the change in the internal energy.

16. An isochoric process is one that occurs at a constant volume
An isochoric process is one that occurs at a constant volume. If heat is added and the volume stays constant, pressure increases, but no work is done since the walls do not move. The first law shows that the heat only changes the internal energy of the system: ∆U = Q + W = Q .

17. An isothermal process is one that takes place at constant temperature.

18. An adiabatic process is one that occurs without the transfer of heat
An adiabatic process is one that occurs without the transfer of heat. Q equals zero, so: ∆U = Q + W = W.

19. A process may be too complex to be recognizable as one of the previous situations. The area under a pressure-volume graph is the work done for any kind of process. This area can be calculated using integral calculus.

20. For the adiabatic expansion or compression of a monatomic ideal gas: W = 3/2 • nR(Ti - Tf). When the gas expands, W is negative and Ti must be greater than Tf. When the gas is compressed, W is positive and Ti must be less than Tf.