text: First Example: Let gas 1 be H and gas 2 be O. (This example is solving for the ratio between the rates of the two gases)
  Therefore, hydrogen molecules effuse four times faster than those of oxygen.
  Graham's Law can also be used to find the approximate molecular weight of a gas if one gas is a known species, and if there is a specific ratio between the rates of two gases (such as in the previous example).  The equation can be solved for the unknown molecular weight.
  Graham's law was the basis for separating uranium-235 from uranium-238 found in natural uraninite (uranium ore) during the Manhattan Project to build the first atomic bomb. The United States government built a gaseous diffusion plant at the Clinton Engineer Works in Oak Ridge, Tennessee, at the cost of $479 million (equivalent to $ in ). In this plant, uranium from uranium ore was first converted to uranium hexafluoride and then forced repeatedly to diffuse through porous barriers, each time becoming a little more enriched in the slightly lighter uranium-235 isotope.
  Second Example: An unknown gas diffuses 0.25 times as fast as He. What is the molar mass of the unknown gas?
  Using the formula of gaseous diffusion, we can set up this equation.
  Which is the same as the following because the problem states that the rate of diffusion of the unknown gas relative to the helium gas is 0.25.
  Rearranging the equation results in