Worksheet – Gases II (Combined Gas Law, Ideal Gas Law, and Dalton’s Law of Partial
Pressure)
Combined Gas Law:
PV
 cons tan t
T
1. A gas takes up a volume of 17 liters, has a pressure of 2.3 atm, and a temperature of 299 K. If I raise
the temperature to 350 K and lower the pressure to 1.5 atm, what is the new volume of the gas?
2. If I have 2.9 L of gas at a pressure of 5 atm and a temperature of 50 0C, what will be the temperature of
the gas if I decrease the volume of the gas to 2.4 L and decrease the pressure to 3 atm?
3. I have an unknown volume of gas held at a temperature of 115 K in a container with a pressure of 60
atm. If by increasing the temperature to 225 K and decreasing the pressure to 30 atm causes the
volume of the gas to be 29 liters, how many liters of gas did I start with?
4. If I have 21 liters of gas held at a pressure of 78 atm and a temperature of 900 K, what will be the
volume of the gas if I decrease the pressure to 45 atm and decrease the temperature to 750 K? [30.3L]
5. A scuba diver inhales a lung-full (350 mL) of air at a depth of 33 ft where the pressure is approximately
2.0 atm and the water temperature is 18°C. If the diver holds her breath (not a good idea!!), what
volume will the same amount of air occupy at sea level where the pressure is approximately 1.0 atm
and the air temperature is 35°C? [741mL]
Avogadro’s Principle:
6. For ideal gases, Avogadro’s principle states that equal volumes of different gases, at the same
temperature and pressure, contain the same number of gas molecules.
7. According to Avogadro’s principle, how will the number of molecules in 2 liters of hydrogen gas
compare with the number of molecules in 2 liters of oxygen gas at the same temperature and
pressure? Exactly the same number of gas molecules or moles.
Ideal Gas Law:
PV
 nR
T
1. If I have 4 moles of a gas at a pressure of 5.6 atm and a volume of 12 liters, what is the temperature?
2. If I have an unknown quantity of gas at a pressure of 1.2 atm, a volume of 31 liters, and a temperature
of 87 0C, how many moles of gas do I have?
3. If I contain 3 moles of gas in a container with a volume of 60 liters and at a temperature of 400 K, what
is the pressure inside the container?
4. If I have 2.4 moles of gas held at a temperature of 97 0C and in a container with a volume of 45 liters,
what is the pressure of the gas? [1.63 atm]
5. If I have 72 liters of gas held at a pressure of 3.4 atm and a temperature of 225 K, how many moles of
gas do I have? [13.2 mol]
6. It is not safe to put aerosol canisters in a campfire, because the pressure inside the canisters gets very
high and they can explode. If I have a 1.0 liter canister that holds 2 moles of a gas, and the campfire
temperature is 1400°C, what is the pressure inside the canister? [275 atm]
7. I have a balloon that can hold 100 liters of air. If I blow up this balloon with 3 moles of oxygen gas at a
pressure of 1 atmosphere, what is the temperature of the balloon? [406 K]
Dalton’s Law of Partial Pressure:
8. A metal tank contains three gases: oxygen, helium, and nitrogen. If the partial pressures of the three
gases in the tank are 35 atm of O2, 5 atm of N2, and 25 atm of He, what is the total pressure inside of
the tank?
9. Blast furnaces give off many unpleasant and unhealthy gases. If the total air pressure is 0.99 atm, the
partial pressure of carbon dioxide is 0.05 atm, and the partial pressure of hydrogen sulfide is 0.02 atm,
what is the partial pressure of the remaining air?
10. If the air from problem 2 contains 22% oxygen, what is the partial pressure of oxygen near a blast
furnace?
11. Watch the animation sequence by clicking: http://www.kentchemistry.com/links/GasLaws/dalton.htm
If 60.0 L of nitrogen is collected over water at 40.0 °C when the atmospheric pressure is 760.0 mm Hg,
what is the partial pressure of the nitrogen?
Click here for water vapor pressure table:
http://intro.chem.okstate.edu/1515sp01/database/vpwater.html
12. 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?
13. If I place 3 moles of N2 and 4 moles of O2 in a 35L container at a temperature of 25°C, what will the
pressure of the resulting mixture of gases be?
14. Two flasks are connected with a stopcock. The first flask has a volume of 5 liters and contains nitrogen
gas at a pressure of 0.75 atm. The second flask has a volume of 8L and contains oxygen gas at a
pressure of 1.25 atm. When the stopcock between the flasks is opened and the gases are free to mix,
what will the pressure be in the resulting mixture?