Molecular Speeds (5.3.1)

Question 1

• The molecules in a gas have a distribution of speeds, with the majority near the average speed.

Answer 1

• The molecules in a gas have a distribution of speeds, with the majority near the average speed.

Question 2

• The root-mean-square speed (urms) is related to the temperature and molecular mass of the gas.

Answer 2

• The root-mean-square speed (urms) is related to the temperature and molecular mass of the gas.

Question 3

The molecules in a gas have a distribution of
speeds, with the majority near the average speed.

As the molecular mass of a gas increases, the
distribution of molecular speeds shifts toward lower
averages.

As the temperature of a gas rises, the distribution of
molecular speeds shifts toward higher averages.

Answer 3

The molecules in a gas have a distribution of
speeds, with the majority near the average speed.

As the molecular mass of a gas increases, the
distribution of molecular speeds shifts toward lower
averages.

As the temperature of a gas rises, the distribution of
molecular speeds shifts toward higher averages.

Question 4

The speeds of gases are compared using the rootmean-square speed (urms). The root-mean-square speed is the square root of the mean square speed of the gas particles.

The mean square speed of the gas particles is the
sum of their individual squared speeds, divided by
the number of particles.

By the ideal gas law, the mean square speed is
related to the temperature (T) and molecular mass
(M) of the gas by the universal gas constant (R).

This allows the root-mean-square speed to be
calculated directly, given the temperature and
molecular mass of the gas.

Answer 4

The speeds of gases are compared using the rootmean-square speed (urms). The root-mean-square speed is the square root of the mean square speed of the gas particles.

The mean square speed of the gas particles is the
sum of their individual squared speeds, divided by
the number of particles.

By the ideal gas law, the mean square speed is
related to the temperature (T) and molecular mass
(M) of the gas by the universal gas constant (R).

This allows the root-mean-square speed to be
calculated directly, given the temperature and
molecular mass of the gas.