Graham’s Law of Diffusion & Effusion

• Diffusion- rate at which two gases mix

• Effusion- rate at which a gas escapes through a pinhole into a vacuum

• In both cases the rate is inversely proportional to the square root of the MW of the gas

• Rate ? 1/(MW)0.5

• For 2 gases the rate of effusion of the lighter is:

  Rate = (MWheavy/MWlight)0.5
  

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