Module 3 Intro

Module 3—Behaviour of Gases

Watch and Listen

Watch the following video to see an experimental illustration of the effect of pressure on the volume of a gas. You can toggle between the inquiry and explanatory audio tracks as well.

After you have watched the video, summarize what you observed. Where possible, use data from the video to support the points you make. Share your summary with your teacher.

Read

In the video you observed the effect of exerting a great pressure on the volume of a contained gas. But was there a pattern in changes you observed?

Read “Boyle’s Law” on page 151 in your textbook to learn more about this relationship. Carefully work through COMMUNICATION example 2 on page 151.

Self-Check

SC 1.

Complete the following table by converting each measurement into the other four units.

SC 2. In Vancouver, where the air pressure is 100 kPa, a child is given a 2.5-L balloon. The family then drives to a higher elevation above sea level, where the air pressure is only 85 kPa. If the temperature is the same in both places, what is the volume of the balloon in the higher location?

SC 3. Complete “Practice” questions 6, 8, and 9 on page 152 in your textbook.

SC 4. A sample of gas is initially at a pressure of 53 kPa and has a volume of 1.8 L. Determine the new pressure if the volume of the gas decreases to 1.2 L.

SC 5. A sample of gas is initially at a pressure of 1.3 atm and has a volume of 2.3 mL. Determine the new volume if the pressure of the gas decreases to 1.1 atm.

SC 6. A sample of gas has a volume of 5.0 L. Determine the new volume of the gas if the pressure is tripled.

Self-Check Answers

 

SC 1.

 

kPa	atm	mm Hg	torr	bar
410	4.05	3.08 x 103	3.08 x 103	4.10
50.0	0.493	375	375	0.500
133	1.31	998	998	1.33
103	1.01	770	770	1.03
82.1	0.811	616	616	0.821

 

SC 2. Use Boyle’s law.

 

 

 

SC 3. Questions 6, 8 and 9 on page 152 of your textbook.

6. 
   
   
   
   

   
   According to Boyle’s law, the final pressure of the air is 263 kPa. 

1. Pressure and volume are inversely related. If the pressure on the oxygen decreases, the volume should increase if the temperature and the chemical quantity of air remain constant.
   
   
2. 
   
   
   
   
   
   According to Boyle’s law, the final volume of the balloon will be 0.17 L.

9. 
   
   
   
   

SC 4. First, list all the variables.

 

 

Now, apply Boyle’s law.

 

 

SC 5. First, list all the variables.

 

 

Now, apply Boyle’s law.

 

Note: When doing calculations with Boyle’s law, you may use a variety of units for volume and pressure. Make sure the units are consistent; otherwise the calculations won’t work. V1 and V2 must have identical units (mL in this example), and P1 and P2 must have identical units (atm in this example).

SC 6. Because the pressure is being tripled, call the initial pressure P and the final pressure 3P (3 times the initial pressure).

 

First, list all the variables.

 

 

Now, apply Boyle’s law.