The diagram above shows the distribution of speeds for a sample of N2(g) at 25°C
. Which of the following graphs shows the distribution of speeds for a sample of O2(g)
at 25°C
(dashed line) ?

A

Explanation:

The Maxwell-Boltzmann equation, is the basis for discussion of the kinetic theory of gases. From it we can understand how gases are distributed at a particular temperature.

Let us remember that the kinetic energy of all gases is the same at the same temperature. However, the distribution of gases depends on their molecular weight at that particular temperature.

Heavier molecules are known to move slowly compared to lighter molecules. Heavier molecules generally have a smaller distribution while lighter molecules spread out.

For this reason, oxygen which is heavier than nitrogen has a smaller distribution as shown in the diagram (molar mass of oxygen = 32g/mol) while nitrogen (molar mass 28 g/mol) has a distribution that is more spread out being a lighter molecule. Hence the option chosen.