# Ch 21 Kinetic Theory

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```In the kinetic theory model of an ideal gas,
molecules are viewed as point particles that
collide elastically with the walls of the container.
In this model the temperature of the gas is
associated with:
1)
2)
3)
4)
Total potential energy of the gas.
Total kinetic energy of the gas
Average potential energy of a gas molecule.
Average kinetic energy of a gas molecule.
A sealed box contains an ideal gas. The gas is
heated until the pressure doubles. What has
happened to the average speed of each
molecule? That is, what is vf/vi?
For which process is W the largest?
For which process is W the smallest?
For which process is Q the largest?
For which process is Q the smallest?
Molar Specific Heats
πΆπ
πΎ≡
πΆπ£
Two pistons initially have equal volumes of gas
at room temperature. Piston A has a monatomic
gas. Piston B has a diatomic gas. Both pistons
are set to compress their gas to &frac12; the original
volume adiabatically. Which compression
requires more pressure?
Equipartition of Energy
Each degree of freedom contributes
1
π π
2 π΅
of energy per molecule.
Problem
A system of monatomic ideal gas experiences an
adiabatic expansion that moves it from an initial
state, at 400 K, to a final state at a temperature
of 200 K. The process is shown on the P-V
diagram below. Calculate the
a) final pressure.
b) final volume.
c) work done on the gas.
```