Name___________________________
Hour__________
The Behavior of Gases
Practice A
1
Objective 1:
Apply Boyle’s Law, Charles’s Law, and Gay-Lussac’s Law to solve problems
involving pressure and volume and temperature.
Directions: Solve the following problems. Show all your work, including units within
the problem.
1. A high-altitude balloon contains 50 Liters of helium gas at 109 kPa. What is the
volume when the balloon rises to an altitude where the pressure is only 0.25
atm? (Assume that the temperature remains constant.)
2. If a sample of gas occupies 9.2 Liters at 325 Celsius, what will be its volume at
25 Celsius if the pressure does not change?
3. The gas left in a used rigid aerosol can is at a pressure of 103 kPa at 25 Celsius.
If this can is thrown onto a fire, what is the pressure of the gas, in kPa, when its
temperature reaches 928 Celsius?
4. Exactly 10 Liters of air at – 50 Celsius is warmed to 100 Celsius. What is the
new volume if the pressure remains constant?
5. A sample of gas occupies 350 milliliters at a pressure of 3 atm. The gas is
allowed to expand to 700 milliliters while holding temperature constant. What
is the new pressure of the gas, in mm Hg?
Score: _______________________
2
Objective 2: Apply the combined gas law to problems involving pressure,
temperature and volume.
Directions: Solve the following problems. Show all your work, including units within
the problem.
1. A gas at 155 kPa and 20 Celsius occupies a container with an initial volume of 2
Liters. By changing the volume, the pressure of the gas increases to 790 kPa as
the temperature is raised to 120 Celsius. What is the new volume?
2. A 10 Liter air sample at a temperature of – 78 Celsius has a pressure of 2.75
atmospheres. What will be the new pressure if the temperature is raised to 100
Celsius and the volume expands to 25 Liters?
3. A given mass of air has a volume of 6 Liters at 790 mm Hg at a temperature of
30 Celsius. What will the new temperature be (in Celsius) if the gas is allowed
to expand to 15 Liters and the pressure drops to 0.75 atmospheres?
4.
A gas was collected over water, and the following data was obtained: Total
pressure of both gases in container = 1.5 atm; temperature of water = 23 C;
volume of gas = 35 mL. Calculate the volume of the DRY gas at STP conditions.
5.
A gas was collected over water, and the following data was obtained:
Atmospheric pressure = 745 mm Hg; volume of gas = 100 mL; temperature of
the water = 30 C. Calculate the volume of the DRY gas at STP conditions
Score: _________________________
3
Objective 3: Apply the ideal gas law to problems involving pressure, volume,
temperature and the number of moles.
Directions: Solve the following problems. Show all your work, including units within
the problem.
1. You fill a rigid steel cylinder that has a volume of 350 milliliters with nitrogen
gas to a final pressure of 25 atmospheres at 30 Celsius. How many grams of
nitrogen gas does the cylinder contain?
2. What pressure, in kPa, will be exerted by 10 grams of oxygen gas at 25 Celsius if
it is contained in a 0.73 Liter vessel?
3. What volume will 50 grams of argon gas occupy at 25 Celsius and a pressure of
750 mm Hg?
4.
What is the temperature, in Celsius, of 30 grams of helium gas, exerting a
pressure of 1.3 atm contained in a 1500 mL vessel?
5.
How many moles of neon gas are contained in a 50 mL vessel, exerting a
pressure of 110 kPa, at a temperature of 50 Celsius degrees?
Score: _________________
4
Objective 4: Apply Graham’s Law to solve problems involving rates of effusion of
gases.
Directions: Solve the following problems. Show all your work, including units within
the problem.
1. Place the following gases in order of increasing average molecular speed at 300
Kelvin.
Carbon monoxide, sulfur hexafluoride, chlorine gas, hydrogen bromide.

Write their formulas in your answer.
2. Calculate the ratio of the velocity of helium atoms to the velocity of chlorine
molecules at the same temperature.
3. A certain gas effuses four times as fast as oxygen gas. What is the molar mass
of the gas?
4. During an effusion experiment, it took 75 seconds for a certain number of moles
of an unknown gas to pass through a tiny hole. Under the same conditions, the
same number of moles of oxygen gas passed through the hole in 30 seconds.
What is the molar mass of the unknown gas?
5. A certain gas, A, traveled 15 cm in a gas diffusion tube in the same time that a
different gas, B, traveled 10 cm. Calculate the experimental ratio of their
velocities.
Which gas is the lighter gas? ______________
Score: ____________
5
Objective 5: Applications of the Ideal Gas Equation (Honors Only)
Directions: Solve the following problems. Show all your work, including units within
the problem.
1.
Calculate the density of sulfur hexafluoride gas at 678 torr and 28 C.
2.
Calculate the molar mass of a vapor that has a density of 7.135 g/L at 12 C and
743 torr.
3.
The molar mass of a volatile substance was determined by the Dumas-bulb
method. The unknown vapor had a mass of 0.543 grams; the volume of the
bulb was 350 cm3, pressure 743 torr, and temperature of 99 C. Calculate the
molar mass of the unknown vapor.
4.
5.
Calculate the density of nitrogen dioxide gas at 0.987 atm and 40 C.
Calculate the molar mass of a gas if 2.5 grams occupies a volume of 1500 mL at
103 kPa and 45 C.
Score: _____________
6
Objective 6: The Gas Laws and Stoichiometry
Directions: Solve the following problems. Show all your work, including units within
the problem.
1.
Magnesium metal reacts with oxygen gas to form solid magnesium oxide.
a. Write the balanced equation.
b. If an enclosure of 0.382 Liters has a partial pressure of oxygen of 3.5 x
10-4 torr at 27 C, what mass of magnesium will react?
c. In the same reaction, how many grams of magnesium oxide form,
assuming an 85% yield?
2. Consider the complete combustion of liquid pentane, C5H12.
a. Write the balanced equation, (each product is gaseous).
b. What volume of oxygen gas, measured at 23 C and 0.980 atm, is needed
to react with 2.5 grams of pentane?
c. What volume of each product is produced under the same conditions?
Score: _________________
7
Objective 7: Distributed Practice
Directions: Solve the following problems. Show all work, including units within the
problem.
1. What is the density of krypton gas at STP?
2. Hydrogen gas reacts with ethene (C2H4) to form ethane (C2H6) in a combination
reaction.
a. Write the balanced equation:
b. What is the limiting reagent when 40 grams of C2H4 reacts with 3 grams of
hydrogen gas, and how much C2H6 forms?
c. How much excess reagent is left over at the end of this reaction?
3. When magnesium metal reacts with hydrochloric acid, it generates 1500 kJ of
heat energy.
a. Write the balanced thermochemical equation.
b. Draw an enthalpy diagram.
c. How many grams of magnesium must react to liberate 500 kJ of heat
energy?
Score: ___________________
8