1. Use your textbooks to complete the chart below on page 122 in your ISN
Boyle’s Law
Charles’s Law
Gay-Lussac’s Laws
Definition
Formula
Explanation

2. Quick Write p124: What happens when volume is increased inside of a balloon?

3. Class Norms Honor time limits Actively participate (Have S.W.A.G.)
Listen respectfully to your colleagues
Place cell phones on vibrate or silent mode
Participants may write burning questions on a sticky note and place on the parking lot
BE PRESENT (Developing H.O.T.S. for Science)
Class Norms

4. Parking Lot
Burning Issues
Questions
Comments
Ideas to Share

5. Boyle’s Law

6. What is Boyle’s Law?
Boyle’s Law is one of the laws in physics that concern the behavior of gases
When a gas is under pressure it takes up less space
The higher the pressure, the smaller the volume
Boyles Law tells us about the relationship between the volume of a gas and its pressure at a constant temperature
The law states that pressure is inversely proportional to the volume

7. How can we write Boyle’s Law as a formula?
Pressure is inversely proportional to the volume and can be written as:
Pressure a 1/volume
P=pressure in N/m2
V=volume in dm3 (litres)
k=constant
This is more usually written as:
Pressure = constant
volume
PV=k
P1V1=P2V2

8. How can we investigate Boyle’s Law?
When investigating Boyles law a given volume of gas is sucked into a cylinder and the end is sealed
The temperature of the gas is kept constant
Using several equal weights we can apply increasing pressure to the gas
We can calculate the pressure by dividing the force applied by the area of the top of the cylinder
The volume will be shown on the scale on the cylinder

9. Boyle’s Law Apparatus

10. Below are some results of an experiment
Pressure p
Volume V
P x V
1.1 40 44
1.7 26
2.2 20
2.6 17
Calculate pV (pressure x volume) for each set of results. What do you notice?

11. What these experimental results show
The pressure x volume for each set of results remains constant
This is called Boyle’s Law
For a fixed mass of gas, at constant temperature, pV = constant or
P1 x V1 = P2 x V2
Let us look at the results again

12. Here are the results of the experiment
Pressure p
Volume V
P x V
1.1 40 44
1.7 26
2.2 20
2.6 17
Did you notice that if p is doubled, V is halved?
If p increases to 3 times as much, V decreases to a 1/3rd . This means:
Volume is inversely proportional to pressure, or
V  1 p

13. What sort of graphs would this data give?
If we plot volume directly against pressure we would get a downwards curve showing that volume gets smaller as the pressure gets larger, and vice versa.

14. Another way of plotting the data
Curved lines are hard to recognize, so we plot the volume against the reciprocal of pressure (i.e. 1/p)
This time the points lie close to a straight line through the origin.
This means volume is directly proportional to 1/pressure or volume is inversely proportional to pressure

15. This leads us back to Boyle’s Law
Boyle’s Law: for a fixed mass of gas kept at constant temperature the volume of the gas is inversely proportional to its pressure.

16. Problem:
A deep sea diver is working at a depth where the pressure is 3.0 atmospheres. He is breathing out air bubbles. The volume of each air bubble is 2 cm2. At the surface the pressure is 1 atmosphere. What is the volume of each bubble when it reaches the surface?

17. How we work this out:
We assume that the temperature is constant, so Boyle’s Law applies:
Formula first: P1 x V1 = P2 x V2
Then numbers:= 1.0 x 2 = 3.0 x V2
Now rearrange the numbers so that you have V2 on one side, and the rest of the numbers on the other side of the ‘equals’ symbol.

18. Here’s what you should have calculated
V2 = 3.0 x 2
1.0
therefore volume of bubbles = 6 cm3
Note that P1 and P2 have the same unit, as will V1 and V2

19. Boyle’s Law Worksheet: ISN p 123
Abbreviations atm – atmosphere mm Hg - millimeters of mercury torr - another name for mm Hg Pa - Pascal (kPa = kilo Pascal) K - Kelvin °C - degrees Celsius
Conversions K = °C cm3 (cubic centimeter) = 1 mL (milliliter) 1 dm3 (cubic decimeter) = 1 L (liter) = mL Standard Conditions 0.00 °C = 273 K 1.00 atm = mm Hg = kPa = 101,325 Pa
Problems:
A gas occupies 12.3 liters at a pressure of 40.0 mm Hg. What is the volume when the pressure is increased to 60.0 mm Hg?
2. If a gas at 25.0 °C occupies 3.60 liters at a pressure of 1.00 atm, what will be its volume at a pressure of 2.50 atm?
3. A gas occupies 1.56 L at 1.00 atm. What will be the volume of this gas if the pressure becomes 3.00 atm?
4. A gas occupies 11.2 liters at atm. What is the pressure if the volume becomes 15.0 L?
mL of a gas is collected at mm Hg. What will the volume be at standard pressure?
6. Convert mL at mm of Hg to its new volume at standard pressure.
7. Convert 338 L at 63.0 atm to its new volume at standard pressure.