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~ UNIT 4 • ACTIVITY 77lEI Boyle's Law Problems

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Boyle's law states that at a constant temperature, the volume of a sample of gas is inverselyproportional to its pressure. This means that if you know the pressure and volume of a gas at a gi'temperature, you can determine its new volume if you know the pressure it is being changed to. Ifknow the new volume, you can likewise determine the new pressure. The formula looks like this:

PI VI = P2V2where

PI = initial pressure in kilopascals (kPa)

VI = initial volume in liters or a cubic measure like m3

P2 = new pressure in kilopascals

V2 = new volume in liters or a cubic measure like m3

Complete the following Boyle's law problems. Assume that all take place at a constant ternperan

L 400 drrr' of CO2 has a pressure on it of 150 kPa. What will its volume be at 425 kPa?

2. 55 L of gas has a pressure of 95 kPa. What is the pressure when it occupies 25 L?

3. A gas occupies 300 L at 68 kPa. What volume will it occupy at 900 kPa?

4. At 250 kPa, a sample of methane gas, CH4, occupies 25 drrr'. What pressure will it be under

when it occupies 1.5 drrr'?

5. What volume will a sample of water vapor occupy if a 0.055 crrr' sample at 144 kPa has its

pressure increased to 288 kPa? _

IIlJIUnit 4: TopICS in Chemistry· Chemistry© 2005 Walch Publishing

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~ UNIT 4 • ACTIVITY 78lEI Charles's Law Problems

Charles's law states that at a constant pressure, the volume of a sample of gas is directly proportional ~to its Kelvin temperature. This means that if you know the volume and Kelvin temperature of a gas,you can calculate its new volume if you know the temperature it is being changed to. You can alsocalculate the new temperature if you know the new volume it is being changed to. The formula lookslike this:

VI V2---TI - T2

where

VI = initial volume in kilopascals (kPa)

TI = initial temperature in Kelvin

V2 = new volume in kilopascals

T2= new temperature in Kelvin

Complete the following Charles's law problems. Assume they all take place at constant pressure.

L What volume will a 30 L sample at 244 K occupy ifits temperature is raised to 373 K?

2. What is the temperature of a 125 L sample of CO2 at 255 K if its volume is lowered to 111 L?

3. What is the volume of a 35 m3 sample of H20 at 370 K that has its temperature lowered to 350 K?

4. What will the temperature change to if a 400 crrr' sample of gas at 155 K has its volumeincreased to 500 crrr'? -----------------------------------------------

5. What temperature would be needed to increase the volume of 0.0055 m3 of gas at 300 K to0.0075 rrr'? ----------~-------------------------------------------

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Unit 4: Topics in ChemistrY· Chemistry © 2005 Walch Publishing

Investigation llI- Moving Matter Lesson 4 -Egg in a Bottle

Homework - Investigation III - Lesson 41. A gas is collected in a container at a temperature of 22.0°C and 1.0 atm of

pressure. Then the temperature is changed to 25.0°e. What is the new pressure?

2. A gas has a pressure of 0.370 atmospheres at 50.0°e. What is the pressure of thegas at O°C?

3. A sample of gas at 110 atm of pressure inside a steel tank is cooled from 500.0°Cto 0.00°e. What is the final pressure of the gas in the steel tank?

4. A scuba tank is at an initial pressure of 120.0 atm. Calculate the final pressureinside the tank after it cools from 1,000 °C to 25.0°e.

5. If a gas in a closed container is pressurized from 15.0 atm to 18.0 atm and itsoriginal temperature was 25.0°C, what would the final temperature of the gas be?

6. A gas is contained in a tank so that its volume does not change. If the temperatureof the gas is doubled, what would happen to the pressure? Pretend the gas startedout at 273 K.

200 Weather © UC Regents, LHS Living by Chemistry, 2003.