1. TOPIC: BOYLE’S LAW
Do Now: According to the KMT, Why do gases exert pressure
Answer: Gas particles are in constant motion, pushing on the walls of their containers (this force causes pressure)

2. REVIEW: What 4 variables are used to describe gas-phase systems
1. Pressure 2. Volume 3. Temperature 4. Amount gas (moles)

3. BOYLE - 1662 What happened when increased the pressure on the syringe?
CONSTANT: Temperature and Amount
VARIABLES: Pressure and Volume
What happened when increased the pressure on the syringe?

4. Volume cm3)
Pressure (atm)

5. Boyles found that As pressure increase, volume decrease
This is known as an INVERSE RELATIONSHIP (one goes up, the other goes down.
Graph is a hyperbola

6. PressureVolume (atm-cm3)
800
200 4
267 3
400 2 1
PressureVolume (atm-cm3)
Volume (cm3)
Pressure (atm)
Trial
For given T and # moles, pressure x volume always equals same number – product is CONSTANT!

7. Boyle’s Law - words
volume of sample of gas is inversely proportional to its pressure, at constant temperature and # moles

8. Boyle’s Law - mathematically
P X V = K [K = constant]
Can rearrange: V = K/P or P = K/V
For every point on hyperbola:
P x V = same constant, K

9. Can solve word problems to find new pressure/volume when original pressure/volume changes by using following formula:
P1V1 = P2V2

10. A sample of oxygen gas occupies a volume of 250 ml at 740 torr pressure. What volume will it occupy at 800 torr pressure?
P1V1 = P2V2
740 torr * 250ml = 800 torr * V2 ml