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.

Q1:

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).

Q2:

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

Q3:

All gases can condense into a liquid or solid below a critical temperature ๐‘‡ C . Which of the following statements is true?

  • AThe value of ๐‘‡ C does not depend on the gas pressure.
  • BBelow ๐‘‡ C , the kinetic energy of the molecules is zero.
  • CAbove ๐‘‡ C , the potential energy of the intermolecular interactions is zero.
  • DBelow ๐‘‡ C , 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 ๐‘‡ C to decrease.

Q4:

The velocities, ๐‘ฃ , 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.

Nagwa uses cookies to ensure you get the best experience on our website. Learn more about our Privacy Policy.