Chapter 2, Question 51 If a gas line springs a leak, which will diffuse faster through the atmosphere and why: CH4 or C2H6? 1/2 Rates of diffusion and effusion depend on the masses of the gases because average speeds determine these rates, and these are given by Equation 2-5: Trms = 3RT M For two gases at the same temperature, the one with the smaller mass has the molecular speed and will diffuse Thus, CH4 diffuses through the atmosphere than C2H6