Name _______KEY__________________________________ Date _________ Period ______
Graham’s Law
1.
Compare and contrast diffusion and effusion.

2.
What gas property has the biggest effect on its rate of diffusion and effusion?

3.
Diffusion is the spread of molecules from an area of high pressure to low.
Effusion is the movement of gas through a small hole.
The Molar Mass of the gas has the biggest effect on diffusion/effusion rate.
Determine the relative rate of diffusion of argon to helium.
Rate a
molar mass b Rate Ar
4.00 g/mol
=√
;
=√
= 0.316
Rate b
molar mass a Rate He
39.95 g/mol
4.
Compute the relative effusion rate of chlorine to hydrogen. (Note: Both gases are
diatomic.)
Rate a
molar mass b Rate Cl2
2.02 g/mol
=√
;
=√
= 0.169
Rate b
molar mass a Rate H2
70.90 g/mol
5.
How much faster will N2 effuse than O2?
Rate a
molar mass b Rate N2
32.00 g/mol
=√
;
=√
= 1.07
Rate b
molar mass a Rate O2
28.02 g/mol
6.
How much slower will S diffuse than He?
Rate a
molar mass b
Rate S
4.00 g/mol
=√
;
=√
= 0.353
Rate b
molar mass a Rate He
32.07 g/mol
7.
Challenge Question
A certain gas effuses 4 times as fast as oxygen gas. What is the molar mass of the
unknown gas?
Rate a
molar mass b Rate X
32.00 g/mol
=√
;
=4=√
= 2.00 g/mol
Rate b
molar mass a Rate O2
X g/mol