1. Gas Laws
Section 3.2

2. Gas and Pressure
Pressure—result of force distributed over an area

3. Gas and Pressure
The wider the arrow, the greater the force. Which has the greatest pressure? The least pressure?

4. What causes pressure? In a gas, it’s all about collisions
Atoms in a gas are constantly moving
Collisions push against container and create pressure

5. What affects pressure? Temperature of gas Volume of gas
Number of particles in gas

6. Temperature and Pressure
Overall, increasing the temperature increases the pressure
Higher temperature increases particle speed
energy
collisions
pressure

7. Volume and Pressure
Overall, decreasing the volume increases the pressure
Less space means more collisions
collisions
pressure

8. Number of Particles and Pressure
Overall, increasing the number of particles increases the pressure
More particles means more collisions
collisions
pressure

9. The Gas Laws
Charles’s Law
Boyle’s Law

10. Charles’s Law
Jacques Charles
Collected data on temperature and volume

11. Charles’s Law
Extended line to hit x-axis
                                                                
                                                                
                                                                

12. Charles’s Law
Temperature at which the volume is 0L is – C, or 0K.
Absolute zero
Volume of gas is directly proportional to the temperature (in Kelvin) if pressure and particle number are same
                                                                
                                                                
                                                                

13. Charles’s Law
V1 = V2
T1 T2
V1 = Initial volume T1= Initial temperature (K)
V2 = Final volume T2= Final temperature (K)

14. Sample Problems Steps: Identify any knowns as either V1, T1, V2, or T2
Make sure that all temperature values are in Kelvin
Plug knowns in equation
Double-check that answer and units make sense

15. A sample of gas at 101. 3kPa had a volume of 1. 2L at 100oC
A sample of gas at 101.3kPa had a volume of 1.2L at 100oC. What would its volume be at 0oC at the same pressure?
Vf = 0.88L
A balloon had a volume of 75L at 25oC. To what does the temperature need to raised in order for the balloon to have a volume of 100L at the same pressure?
Tf = 124oC

16. Boyle’s Law
Robert Boyle
Collected data on pressure and volume

17. Boyle’s Law

18. Boyle’s Law
Volume of gas is inversely proportional to the pressure if the volume and particle number are same

19. Boyle’s Law P1V1 = P2V2 V1 = Initial volume P1= Initial pressure
V2 = Final volume R2= Final pressure

20. Sample Problems Steps: Identify any knowns as either V1, P1, V2, or P2
Plug knowns in equation
Double-check that answer and units make sense

21. The volume of the lungs is measured by the volume of air inhaled or exhaled.  If the volume of the lungs is L during exhalation and the pressure is KPa, and the pressure during inhalation is KPa, what is the volume of the lungs during inhalation?
2.441 L
It is hard to begin inflating a balloon.  A pressure of Kpa is required to initially inflate the balloon mL.  What is the final pressure when the balloon has reached it's capacity of 1.2 L?
150 Kpa

22. Combined Gas Law
Describes the relationship between the temperature, volume, and pressure of a gas when the number of particles is constant

23. Combined Gas Law P1V1 = P2V2 T1 T2
V1 = Initial volume V2 = Final volume
T1 = Initial temperature (K) T2 = Final temperature (K)
P1 = Initial Pressure P2 = Final Pressure

24. A gas takes up a volume of 17 liters, has a pressure of 2
A gas takes up a volume of 17 liters, has a pressure of 2.3 atm, and a temperature of 299 K. If I raise the temperature to 350 K and lower the pressure to 1.5 atm, what is the new volume of the gas?
30.6 L
If I have 17 liters of gas at a temperature of 67 0C and a pressure of atm, what will be the pressure of the gas if I raise the temperature to 94 0C and decrease the volume to 12 liters?
136 atm
If I have 2.9 L of gas at a pressure of 5 atm and a temperature of 50 0C, what will be the temperature of the gas if I decrease the volume of the gas to 2.4 L and decrease the pressure to 3 atm?
160 K

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