Gas Law Worksheet
Easy Problems
1. A container holds three gases with a total pressure of 10 atm. Oxygen, with a
mole fraction of 0.2, carbon dioxide with a mole fraction of 0.3 and helium
with a mole fraction of 0.5. What are the partial pressures of the three gases?
2. Calculate the volume 3.00 moles of a gas will occupy at 297 K and 762.4 mm
Hg. Use 62.4 for R.
3. A gas has a volume of 800.0 mL at 250 K and 300.0 torr. What would the
volume of the gas be at 500 K and 600.0 torr of pressure?
Medium Problems
1. 80.0 liters of oxygen is collected over water at 50.0 °C. The atmospheric
pressure in the room is 96.00 kPa. What is the partial pressure of the oxygen?
2. How many moles of gas are contained in a 50.0 L cylinder at a pressure of
100.0 atm and a temperature of 35.0 °C?
3. A gas balloon has a volume of 106.0 liters when the temperature is 45.0 °C
and the pressure is 740.0 mm of mercury. What will its volume be at 20.0 °C
and 780 .0 mm of mercury pressure?
Hard Problems
1. A mixture of 14.0 grams of hydrogen, 84.0 grams of nitrogen, and 2.0 moles
of oxygen are placed in a flask. When the partial pressure of the oxygen is
78.00 mm of mercury, what is the total pressure in the flask?
2. A 50.00 liter tank at minus 15.00 °C contains 14.00 grams of helium gas and
10.00 grams of nitrogen gas.
a. Determine the moles of helium gas in the tank.
b. Determine the moles of nitrogen gas in the tank.
c. Determine the mole fraction of helium gas in the tank.
d. Determine the mole fraction of nitrogen gas in the tank.
e. Determine the partial pressure of helium gas in the tank.
f. Determine the partial pressure of nitrogen gas in the tank.
g. Determine the total pressure of the mixture in the tank.
h. Determine the volume that the mixture will occupy at STP.
3. 45.0 mL of wet argon gas is collected at 729.3 mm Hg and 25.0 °C. What
would be the volume of this dry gas at standard conditions?
Answers to Gas Law Worksheet
Easy Problems
1. Oxygen has a partial pressure of 2 atm, carbon dioxide has a partial pressure
of 3 atm, and helium has a partial pressure of 5 atm.
2. PV=nRT = (762.4)(?)=(3.00)(62.4)(297) = 72.93 L.
3. (P1V1/T1) = (P2V2/T2) = (300.0)(800.0)/(250) = (600.0)(?)/(500) = 800 mL.
Medium Problems
1. 96.00 kPa - 12.33 kPa = 83.67 kPa
2. n = PV / RT
n = [ (100.0 atm) (5.00 L) ] / [ (0.08206 L atm mol K) (308.0 K) ] = 19.79 mol
3. (P1V1/T1) = (P2V2/T2) = (P1V1/T1) = (P2x/T2)
x = [ (740 mmHg) (106 L) (293 K) ] / [ (318 K) (780 mmHg) ] = 92.67 L
Hard Problems
1. (14.0 g / 2.00 g/mol) + (84.0 g /28.0 g/mol) + (2.0 moles) = 12.0 moles total
Mole fraction of oxygen = 2 mol/12 total mol = .167
If partial pressure = (mole fraction)(total pressure) then total pressure = partial
pressure/mole fraction. So, total pressure = 78.00/.167 = 467.0 mm Hg.
2. a. 14.0 g / 4.00 g mol = 3.50 mol
b. 49.0 g / 28.0 g mol = 1.75 mol
c. 3.50 mol / 5.25 mol = .667
d. 1.75 mol / 5.25 mol = .333
e. Find the total pressure using PV=nRT, then multiply it by helium’s mole
fraction. P = nRT / V.
P = [ (5.25 mol) (0.08206 L atm mol K) (258.0 K) ] / 50.00 L = 2.223
2.223 multiplied by .667 = 1.48 mm Hg.
f. Multiply the mole fraction of nitrogen found in d. by the total pressure
found in e. .333 multiplied by 2.223 = .740 mm Hg.
g. Already found in e. It is 2.223 mm Hg
h. Change the formula to V = nRT / P.
V = [ (5.25 mol) (0.08206 L atm mol¯1 K¯1) (273.0 K) ] / 1.00 atm = 117.6 L
3. Subtract the water vapor pressure of 23.8 mm Hg from 729.3 mm Hg to get
just the argon pressure of 665.3mm Hg.
x = [ (665.3 mm Hg) (19.1 L) (273 K) ] / [ (291.5 K) (760 mm Hg) ] =
15.66 L or 15,660 mL.