When a space capsule returns to earth, its surfaces get very hot as it passes through the atmosphere at high speed. Has the space capsule been heated? If so, what was the source of the heat? If not, why is it hot?

Do (a) temperature, (b) heat, and (c) thermal energy describe a property of a system, an interaction of the system with its environment, or both? Explain.

Two containers hold equal masses of nitrogen gas at equal temperatures. You supply 10 J of heat to container A while not allowing its volume to change, and you supply 10 J of heat to container B while not allowing its pressure to change. Afterward, is temperature $T_{\text{A}}$ greater than, less than, or equal to $T_{\text{B}}?$ Explain.

You need to raise the temperature of a gas by $10\text{°}\text{C}$. To use the least amount of heat energy, should you heat the gas at constant pressure or at constant volume? Explain.

Why is the molar specific heat of a gas at constant pressure larger than the molar specific heat at constant volume?

FIGURE Q19.6 shows an adiabatic process.

1. Is the final temperature higher than, lower than, or equal to the initial temperature?

2. Is any heat energy added to or removed from the system in this process? Explain.

FIGURE Q19.6

FIGURE Q19.7 shows two different processes taking an ideal gas from state i to state f. Is the work done on the gas in process A greater than, less than, or equal to the work done in process B? Explain.

FIGURE Q19.7

FIGURE Q19.8 shows two different processes taking an ideal gas from state i to state f.

1. Is the temperature change $\text{Δ}T$ during process A larger than, smaller than, or equal to the change during process B? Explain.

2. Is the heat energy added during process A greater than, less than, or equal to the heat added during process B? Explain.

FIGURE Q19.8

The gas cylinder in FIGURE Q19.9 is a rigid container that is well insulated except for the bottom surface, which is in contact with a block of ice. The initial gas temperature is $>0\text{°}\text{C}$.

1. During the process that occurs until the gas reaches a new equilibrium, are (i) $\text{Δ}T$, (ii) $W$, and (iii) $Q$ greater than, less than, or equal to zero? Explain.

2. Draw a pV diagram showing the process.

FIGURE Q19.9

The gas cylinder in FIGURE Q19.10 is well insulated except for the bottom surface, which is in contact with a block of ice. The piston can slide without friction. The initial gas temperature is $>0\text{°}\text{C}$.

1. During the process that occurs until the gas reaches a new equilibrium, are (i) $\text{Δ}T$, (ii) W, and (iii) $Q$ greater than, less than, or equal to zero? Explain.

2. Draw a pV diagram showing the process.

FIGURE Q19.10

The gas cylinder in FIGURE Q19.11 is well insulated on all sides. The piston can slide without friction. Many small masses on top of the piston are removed one by one until the total mass is reduced by 50%.

1. During this process, are (i) $\text{Δ}T$, (ii) W, and (iii) $Q$ greater than, less than, or equal to zero? Explain.

2. Draw a pV diagram showing the process.

FIGURE Q19.11