1. Gas Laws

2. Gas Pressure
Gas pressure is the result of gas particles colliding with the walls of the container
If the volume and temperature of the container is constant:
If gas is added, pressure increases
If gas is removed, pressure decreases

3. Gas Pressure
Gas molecules move from an area of higher pressure to area of lower pressure
Opening a can/bottle of soda

4. Gas Laws Predict the behavior of gases based on four properties:
Amount of gas (moles)
Pressure
Temperature
Volume
If one of these properties change, the others change as well.

5. Boyle’s Law Irish Chemist
Noticed there is an inverse relationship between the pressure and volume of a gas
if the temperature and moles of the gas are constant
If pressure increases, volume decreases
If volume increases, pressure decreases
P1V1 = P2V2

6. Boyle’s Law Continued
P1V1 = P2V2

7. Practice
Air in a container occupies mL at 1.08 atm. What volume must the container be to have a pressure of 1.43 atm? mL

8. Practice
A balloon filled with He has a volume of 4.0L has a pressure of 210 kPa. If the balloon is compressed to 2.5 L, what will the pressure of He inside the balloon?
Answer: 336 kPa

9. Practice
The volume of a gas at 99.0 kPa is 300 mL. If the pressure is increased to 188 kPa, what is the new volume?
Answer: mL
The pressure of a sample of He in a 1.00 L container is atm. What is the new pressure if the sample is placed in a 2.00 L container?
Answer: atm

10. Kelvin Scale and Charles’ Law

11. Temperature Scales SI scale: degree Celsius (°C) or Kelvin (K)
English scale: degree Fahrenheit (°F)
°C = Temperature in Kelvin
Kelvin – 273 = temperature in °C
Kelvin scale is based off the Celsius scale.
At 0 K all matter is believed to stop moving
Absolute Zero

12. Charles’ Law Jacque Charles- French Physicist
Noticed that the volume of the a gas increased when it is heated, under constant pressure
Direct relationship between temperature and volume

13. Charles’ Law

14. Practice
A gas sample at 40.0°C occupies 2.32 L. If the temperature is raised to 75°C, what is the volume of the gas if pressure is constant?
Answer: 4.35 L
A gas at 89°C occupies 0.67 L. If the volume is increased to 1.12 L, what the temperature be in degree Celsius?
Answer: °C

15. Practice
The Celsius temperature of a 300 L sample of gas is lowered from 80.0 °C to 30.0 °C. What will be the resulting volume of this gas?
Answer: L
What is the volume of the air in a balloon that occupies L at 25 °C if the temperature is lowered to 0.00 °C. (convert temps. to Kelvin)
Answer: L

16. Lussac’s Law
Joseph Gay-Lussac explored the relationship between temperature and pressure.
Direct relationship

17. Practice
A gas in a sealed container has a pressure of 123 kPa at 30.0°C. If the pressure is increased to 201 kPa, what is the new temperature?
Answer: 49.02°C
The pressure in an automobile tire is 1.88 atm at 25°C. What will be the pressure if the temperature warms to 37°C?
Answer: 2.78 atm

18. Combined Gas Law Combines Boyle’s, Charles’s, and Lussac’s Laws.
Shows the relationship between temperature, pressure, and volume if the amount of gas is held constant.
P1V1 = P2V2

19. Pratice
A He filled balloon at sea level has a volume of 2.1L at atm and 36°C. If it released and rises to an elevation at which the pressure is atm and the temperature is 28°C, what will be the new volume of the balloon?
Answer: 1.81L

20. Practice
At 0.00°C and 1.00 atm pressure, a sample of gas occupies 30.0 mL. If the temperature increased to 30.0°C and the entire gas sample is transferred to a 20.0 mL container, what will the gas pressure inside the container?
Answer: 1.66 atm

21. PV=nRT Ideal Gas Law P- pressure (atm or kPa) V- volume (L)
The properties of a gas under ideal conditions
PV=nRT
P- pressure (atm or kPa)
V- volume (L)
n- moles of gas (moles)
R- ideal gas constant
T- temperature (K)

22. What is the Ideal Gas Constant?
Determined by a series of experiments
Relates pressure, volume, temperature, and moles.
2 Ideal Gas Constants
0.0821
8.314
Which one do you use?
Based on pressure units
If pressure in atm use
If pressure in kPa use 8.314

23. Practice
Calculate the number of moles of a gas in a 3.0 L vessel at 300.K with a pressure of 1.50 atm.

24. Practice
If the pressure exerted by a gas at 25°C in a volume of L is 3.81atm, how many moles of gas are present?
Answer: mol
Determine the Celsius temperature of 2.49 moles of gas contained in a 1 L vessel at a pressure of 143 kPa.
Answer: 6.9 K= -266°C

25. Practice
Calculate the volume that a mol sample of a gas will occupy at 265 K and a pressure of atm.
Answer: 7.8 L
What is the pressure in atmospheres of a mol sample of He gas at a temperature of 20°C if its volume is 0.505L?
Answer: atm

26. Equations and Information
PV=nRT R=
R= 8.314
R= 62.4
P1V1 = P2V2
1 atm = kPa
1 atm = 760 mmHg
Convert All Temperatures To Kelvin