Combined Gas Law Worksheet



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Combined Gas Law

What law do I use if neither temperature, nor pressure, nor volume is constant? Why, the combined gas law of course! The combined gas law is a gas law which combines Charles' law, Boyle's law, and Gay-Lussac's law.

P1V1 = P2V2

T1 T2

*When using the Combined Gas Law you must convert temperature from degrees Celsius to Kelvin.

Use the equation K = ºC + 273

1. At a pressure of 405 kPa and a temperature of 200 K, the volume of a gas is 6.00 cm3. At what pressure will the new temperature and volume be 300 K and 4.00 cm3?

2. At 189 K and a pressure of 600 torr, a sample of nitrogen gas has a volume of 32.0 cm3. What volume does the gas occupy at 242 K and 675 torr?

3. A volume of gas at 1.10 atm was measured at 22°C and 326 cm3. What will be the volume if the gas is cooled to -10°C and the pressure is adjusted to 1.90 atm?

4. The gas in a balloon occupies 2.25 L at 298 K and 300 kPa. At what temperature will the balloon expand to 3.50 L and 220 kPa?

5. A sample of gas has a volume of 852 mL at 25°C and 2.0 atm. What Celsius temperature is necessary for the gas to have a volume and pressure of 945 mL and 1.3 atm?

6. If 36.5 m3 of a gas are collected at a pressure and temperature of 755 mm of Hg and 280 K respectively, what volume will the gas occupy if the pressure and temperature are changed to 632 mm of Hg and 305 K?

7. O2 gas in a canister with a volume of 40 L at 25°C and 0.7 atm is compressed to a volume and pressure of 32.5 L and 1.4 atm. At this new volume and pressure what will the temperature of the gas be in degrees Celsius?

8. At a pressure of 13.6 atm, a gas occupies 62.1 cm3 at a temperature of 80°C. If the temperature is raised to 110 °C, at what volume will the pressure be 8.9 atm?

The Ideal Gas Law (PV = nRT)

In 1834, a more general relationship was derived from the experimentally based research of Boyle, Charles, Gay-Lussac and Avogadro known as the ideal gas law. The amount of gas = n (number of moles of gas). A fifth variable, a constant known as “R” is used in the ideal gas equation and its value is shown below.

atm x L

mol x K

Solve the following problems, using the ideal gas equation.

Remember to convert temperature to Kelvin (K = °C + 273)

9. What volume will 2.50 mol of hydrogen (H2) occupy at -20.0 °C and 1.5 atm?

10. How many moles of sulfur dioxide are held inside a 67.4 L canister at a pressure of 0.25 atm and a temperature of 40.0 °C?

11. At what temperature will a 0.450 L vessel hold 4.0 mol carbon dioxide (CO2) gas at a pressure of 1.25 atm?

12. A neon light bulb (cylinder shaped, with a volume of 0.0026 L) at 0.0 °C and 1 atm contains how

many moles of gas?

13. A balloon contains 25.0 grams helium (He) gas at room temperature (22 °C) and occupies a volume of 75.0 L. How much pressure does the He gas exert on the walls of the balloon?

14. At what temperature will 2.5 mol nitrogen gas exert a pressure of 10.0 atm in a 2.0 L container?

15. Determine the pressure exerted by 0.122 moles of oxygen gas in a 1.50 L container at room temperature (22 °C).

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Example:

A gas at 300 K is heated and expands from 12 L and 600 kPa to 1250 K and 500 kPa. What is the final volume?

P1 = 600 kPa P2 = 500 kPa P1V1T2 = P2V2T1

V1 = 12 L V2 = ?

T1 = 300 K T2 = 1250 K (600 kPa)(12 L)(1250 K) = (500 kPa)V2(300 K)

V2 = (600 kPa)(12 L)(1250 K) = 60 L

(500kPa)(300 K)

R = 0.0821

Example:

What volume will 2.0 mol of oxygen (O2) occupy at 40.0 °C and 0.50 atm?

P = 0.50 atm n = 2.0 mol V = nRT

V = ? T = 40.0°C + 273 = 313 K P

V = (2.0 mol) (0.0821 atm x L) (313 K) = 102.8 L

(0.50 atm) mol x K

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