DALTON’S LAW & GRAHAM’S LAW
1.
Determine the partial pressure of each gas in a container with 2.0 moles of N2, 3.0 moles
of O2, and 7.0 moles of H2 that has a total pressure of 850 mm Hg.  (You will have 3

2. A mixture of nitrogen and oxygen has a total pressure of 730 mm Hg. If the nitrogen has a
partial pressure of 420 mm Hg, find the pressure of the oxygen.

3. At an altitude of 30,000 ft., the total air pressure is only about 450. mm Hg.  If the air is
21.0 % oxygen, what is the partial pressure of oxygen at this altitude?

4. A mixture of 3 gases have the following pressures:  oxygen = 355 mm Hg, helium = 468
mm Hg, and nitrogen = 560 mm Hg.  Find the % of each gas in the mixture.

5. Compare the rate of effusion of CH4 and CO2.  (Give answers to # 5, 6, & 7 to 3 SF's.)
(Your answers for # 5, 6, &, 7 should read " ___  effuses ___ times faster than ___.")

6. Compare the rate of effusion of helium and nitrogen.

7. How much faster does ammonia (NH3) effuse than HCl?

8. An unknown gas effuses 4.0 times faster than O2.  Find the molar mass of the unknown
gas.  * What gas could this be?

Answers:    1.) N2 = 142 mm Hg, O2 = 213 mm Hg, H2 = 496 mm Hg        2.) 310 mm Hg
3.)
94.5 mm Hg        4.) O2 = 25.7%, He = 33.8 %, N2 = 40.5 %
5.) CH4 effuses 1.66 times faster than CO2.        6.) He effuses 2.65 times faster than N2.
7.) NH3 effuses 1.46 times faster than HCl          8.) 2.0 g/mole