In this worksheet, we will practice describing kinetic molecular theory and relating temperatures of gases to the energies of randomly moving molecules.
Which of the following is not a postulate of kinetic molecular theory?
- AThe molecules composing a gas are negligibly small compared to the distances between them.
- BGases are composed of molecules that are in continuous motion, traveling in straight lines and changing direction only when they collide with other molecules or with the walls of a container.
- CThe pressure exerted by a gas in a container results from collisions between the gas molecules and the container walls.
- DGas molecules join together very briefly when they collide, acting as a single molecule.
- EGas molecules exert no attractive or repulsive forces on each other or the container walls; therefore, their collisions are elastic (they do not involve a loss of energy).
Under which of the following conditions does a real gas behave most like an ideal gas?
- ALow temperature, high pressure
- BHigh pressure, small volume
- CSmall volume, low temperature
- DHigh temperature, low pressure
- ELarge volume, low temperature
All gases can condense into a liquid or solid below a critical temperature . Which of the following statements is true?
- AThe value of does not depend on the gas pressure.
- BBelow , the kinetic energy of the molecules is zero.
- CAbove , the potential energy of the intermolecular interactions is zero.
- DBelow , the potential energy of the intermolecular interactions is greater in magnitude than the kinetic energy.
- EMaking the potential energy of intermolecular interactions more negative causes to decrease.
The velocities, , of molecules in a gas vary over a wide range but are strongly affected by their mass. At a particular temperature, heavier molecules move more slowly on average. Shown in the figure are the velocities displayed by different noble gas molecules at room temperature.
If a sample of argon at room temperature is cooled, how and why does the distribution of velocities change?
- AThe mass of the molecules is unaffected by cooling, so the distribution does not change.
- BThe gas molecules occupy a smaller volume, so the distribution changes to resemble neon at room temperature.
- CThe gas molecules gain potential energy, so the distribution changes to resemble neon at room temperature.
- DThe gas molecules lose kinetic energy, so the distribution changes to resemble krypton at room temperature.
- EThe gas molecules interact more strongly, so the distribution changes to resemble krypton at room temperature.