The diffusion of H2 gas through He gas was found to be 5 cm2/s at atmospheric pressures and room temperatures. If we were to switch the He gas to Ar gas, what would be the diffusivity of H2 through Ar. Although you dont need to memorize the entire relationship of the Chapman-Enskog theory, the approximate relationship should have been realized. Ar has a molecular weight of 40 g/mol.