Diffusion

1. Diffusion The spontaneous spreading of particles Rate of diffusion depends on the velocities and masses of the molecules. Effusion- the process by which a gas escapes from a small hole in a container.

2. Two substances at the same temperature should have the same average kinetic energies. KE1=KE2 and KE = ½ mv2 ½ m1v12= ½ m2v22 m1v12= m2v22 v12 =m2 or v22 m1

3. Graham’s Law of Diffusion The relative rates at which two gases (at the same temperature and pressure) will diffuse vary inversely as the square root of the molecular masses of the gases.

4. Compute the relative rate of diffusion of helium and argon. He diffuses 3.16 times faster than Ar.

5. Compare the rates of diffusion of O2 and N2. Since the lighter gas always diffuses faster, N2 diffuses 1.07 times faster than O2.

6. You try it. . . Compare the rates of diffusion of sulfur trioxide and nitrogen monoxide. NO diffuses 1.63 times faster than SO3.

7. Gas #1 weighs 42.0 g/mol and diffuses at a rate of 5.65 m/s through an opening in a jar. Gas #2 weighs 252.0 g/mol. At what rate would it pass through the same opening? 5.65m/s = 2.45 v2 2.31m/s = v2

8. Diffusion Lab NH4OH g H2O + NH3h HCl NH3