Question

Question #6c305

Answer 1

`F_2` being lightest, diffuses fastest. `Cl_2`, being heaviest will diffuse most slowly.

Explanation:

Average kinetic energy of molecules is related to the absolute temperature of the substance made of those molecules. So, if the three gases are at the same temperature, all have the same average KE.

Now, since KE is given by `1/2 mv^2`, it follows that heavier molecules move more slowly on average (at equal temp.). This is the key to diffusion. Rate of diffusion is tied to the speed of the molecules. Faster moving molecules diffuse at a greater rate.