Worksheet: Kinetic Molecular Theory
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?
- AGas 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).
- BGas molecules join together very briefly when they collide, acting as a single molecule.
- CGases 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.
- DThe pressure exerted by a gas in a container results from collisions between the gas molecules and the container walls.
- EThe molecules composing a gas are negligibly small compared to the distances between them.
All gases can condense into a liquid or solid below a critical temperature . Which of the following statements is true?
- ABelow , the kinetic energy of the molecules is zero.
- BAbove , the potential energy of the intermolecular interactions is zero.
- CBelow , the potential energy of the intermolecular interactions is greater in magnitude than the kinetic energy.
- DThe value of does not depend on the gas pressure.
- 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 gas molecules gain potential energy, so the distribution changes to resemble neon at room temperature.
- BThe gas molecules lose kinetic energy, so the distribution changes to resemble krypton at room temperature.
- CThe gas molecules interact more strongly, so the distribution changes to resemble krypton at room temperature.
- DThe mass of the molecules is unaffected by cooling, so the distribution does not change.
- EThe gas molecules occupy a smaller volume, so the distribution changes to resemble neon at room temperature.