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Reviewed CSCA Physics question · Easy

In the kinetic theory of gases, the absolute temperature of an ideal gas is directly proportional to which of the following molecular quantities?

  1. The average speed of the molecules
  2. The average translational kinetic energy of the molecules
  3. The most probable speed of the molecules
  4. The number of molecules per unit volume
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Correct answer

B. The average translational kinetic energy of the molecules

Principle or equation

The average translational kinetic energy of molecules in an ideal gas is proportional to the absolute temperature: KE_avg = (3/2) k_B T.

Why this answer is correct

According to the kinetic theory of gases, the average translational kinetic energy of gas molecules is directly proportional to the absolute temperature. The relationship is KE_avg = (3/2) k_B T, where k_B is the Boltzmann constant. Thus, temperature is a measure of the average translational kinetic energy.

Example

If the temperature of an ideal gas is doubled, the average translational kinetic energy of its molecules doubles as well.

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