PHYS 221 SI Worksheet
(19.58) A certain ideal gas has molar heat capacity at constant volume CV. A sample of this gas initially
occupies a volume V0 at pressure p0 and absolute temperature T0. The gas expands isobarically to a
volume 2V0 and then expands further adiabatically to a final volume 4V0. (a) Draw a pV-diagram,
(b) compute the total work done by the gas, (c) find the final temperature of the gas, and (d) find the
absolute value |Q| of the total heat flow into or out of the gas (and state the direction) for this sequence
of processes.
(19.59) An air pump has a cylinder 0.250 m long with a movable piston. The pump is used to compress
air from the atmosphere (at absolute pressure 1.01E5 Pa) into a very large tank at 4.20E5 Pa gauge
pressure. (For air, CV = 20.8 J/mol·K.) (a) The piston begins the compression stroke at the open end of
the cylinder. How far down the length of the cylinder has the piston moved when air first begins to flow
from the cylinder into the tank? (b) If the air is taken into the pump at 27.0°C, what is the temperature
of the compressed air? (c) How much work does the pump do in putting 20.0 mol of air into the tank?