Consider three identical flasks filled with different gases.
Flask A: CO at 760 torr and 0 degrees Celsius
Flask B: N2 at 250 torr and 0 degrees Celsius
Flask C: H2 at 100 torr and 0 degrees Celsius
In which flask will the molecules have the greatest average kinetic energy? Explain.
In which flask will the molecules have the greatest average velocity? Explain.
Since all three samples are at the same temperature, they will have the the same average kinetic energy. Remember that molecules don't all have the same energy so we compare their average kinetic energy and temperature is a measure of the average kinetic energy.
The molecules with the greatest velocity will be the one with the smallest mass. if the average kinetic energy of each of these will be the same, but the samples have different masses, the sample with the smallest mass must have the greatest velocity. The kinetic energy equals 1/2*m*v^2 so if the mass decreases, the velocity must increase.