What outcome can be expected when two gases are at the same temperature but different molecular weights?

The correct answer indicates that when two gases are at the same temperature, the lighter gas will have a higher average speed compared to the heavier gas. This phenomenon can be understood through the principles of kinetic molecular theory, which states that the average kinetic energy of gas particles is directly proportional to the temperature of the gas.

At a given temperature, all gas molecules have the same average kinetic energy, which can be expressed mathematically as:

[ KE = \frac{1}{2}mv^2 ]

where ( KE ) is the kinetic energy, ( m ) is the mass of the gas molecule, and ( v ) is its speed. Since the average kinetic energy is constant for both gases at the same temperature, a lighter gas, which has a smaller mass, must move at a higher speed to compensate and maintain the same kinetic energy as the heavier gas.

In essence, because the kinetic energy of the particles is the same, the lighter gas's smaller mass means it must have a higher velocity (speed) on average to achieve that equivalent kinetic energy. This leads to the conclusion that the lighter gas will indeed have a higher average speed than the heavier gas when both are at the same temperature.