1. Chapter 13
The Gas Laws

2. Rates of Effusion
Graham’s Law of Effusion:

3. Rates of diffusion Depends mainly on mass of particles involved
Grahams law allows us to compare rates of diffusion of two gasses

4. Ammonia has a molar mass of 17
Ammonia has a molar mass of 17.0 g/mol, hydrogen chloride has a molar mass of 36.5 g/mol. What is the ratio of their diffusion rates?

5. What is the molar mass of a gas that takes four times as long to effuse as hydrogen?

6. Gas Pressure Pressure = force per unit area
Smaller area = more pressure
Air pressure – pressure of the atmosphere
1 atm
760 mm Hg
101.3 kPa

7. Dalton’s law of partial pressures:
Total pressure of a mixture of gasses is equal to the sum of the pressures of all of the gasses in the mixture
P1 + P2 + P3…=Ptotal

8. A mixture of oxygen, carbon dioxide, and nitrogen has a total pressure of 0.97 atm. What is the partial pressure of O2 if the partial pressure of CO2 is 0.70 atm and the partial pressure of N2 is 0.12 atm?

9. 3 factors affecting gases
Temperature
Kelvin = Celsius + 273
Volume L mL
Pressure
kPa
atm
mmHg
Values for pressure units

10. Ping pong ball in hot water video

11. Boyles Law TEMPERATURE CONSTANT
Pressure and volume are inversely related
P1 x V1 = P2 x V2
Relate to KMT

13. A diver blows a 0. 75 L air bubble 10 m under water
A diver blows a 0.75 L air bubble 10 m under water. As it rises to the surface, the pressure goes from 2.25 atm to 1.03 atm. What ill be the volume of the air in the bubble at the surface?

14. The volume of a gas at 99. 0 kPa is 300. 0 mL
The volume of a gas at 99.0 kPa is mL. if the pressure is increased to 188 kPa, what will be the new volume?

15. Charles’s Law PRESSURE CONSTANT Flexible container
Volume and temperature are directly related
Temperature must be in K!
Relate to KMT

17. A helium balloon in a closed car occupies a volume of 2. 32 L at 40
A helium balloon in a closed car occupies a volume of 2.32 L at 40.0 oC. If the car is parked on a hot day and the temperature inside rises to 75.0 oC what is the new volume of the balloon?

18. A gas at 89 oC occupies a volume of 0. 67 L
A gas at 89 oC occupies a volume of 0.67 L. At what Celsius temperature will the volume increase to 1.12 L?

19. Gay-Lussac’s Law VOLUME CONSTANT
Pressure and Temperature are directly related
Temperature must be in K!
Relate to KMT

20. The pressure of the oxygen gas inside a canister is 5. 00 atm at 25
The pressure of the oxygen gas inside a canister is 5.00 atm at 25.0 oC. The canister is located at a camp high on Mount Everest. If the temperature there falls to oC, what is the new pressure inside the canister?

21. Helium gas in a 2. 00 L cylinder is under 1. 12 atm pressure. At 36
Helium gas in a 2.00 L cylinder is under 1.12 atm pressure. At 36.5 oC that same gas sample has a pressure of 2.56 atm. What was the initial temperature of the gas in the cylinder?

22. The Combined Gas Law
The three gas laws discussed can be combined into a single gas law.

23. A gas at 110 kPa and 30.0oC fills a flexible container with an initial volume of 2.00 L. If the temperature is raised to 80.0 oC and the pressure increases to 440 kPa, what is the new volume?

24. A sample of air in a syringe exerts a pressure of 1.02 atm at 22.0 oC. The syringe is placed in a boiling water bath at oC. The pressure is increased to 1.23 atm by pushing the plunger in, which reduces the volume to mL. What was the initial volume?

25. The Ideal Gas Law
Relates number of particles, pressure, temperature, and volume
Avogadro’s principle – equal volumes of gases at the same temperature and pressure contain equal numbers of particles
Talk about 1st part of paragraph

26. Molar volume of a gas is the volume that 1 mol occupies at STP
1 mol of gas = particles
Molar volume of a gas is the volume that 1 mol occupies at STP
STP =
1 mol = 22.4 L of gas

27. How many moles of carbon dioxide gas are in a 1.0 L balloon?
What volume will 9.22 g of H2 gas occupy at STP?

28. The Ideal Gas Law PV = nRT R = 8.31 L*kPa/mol*K R = 0.0821 L*atm/mol*K
Units for each variable

29. Calculate the number of moles of ammonia gas contained in a 2
Calculate the number of moles of ammonia gas contained in a 2.0L vessel at K with a pressure of 1.50 atm

30. What is the volume of a 0. 323 mol sample of a gas at 265 K and 0
What is the volume of a mol sample of a gas at 265 K and atm?

31. How many moles of a gas are in 2.50 L of gas at STP?

32. Real vs. Ideal Gas
Ideal gases follow the assumptions of the kinetic-molecular theory
Particles take up no space
Experience no intermolecular forces
Not attracted to or repelled by the walls of their container
Follow the gas laws under all temperatures and pressures

33. Extreme temperature and pressure
Gases deviate most from ideal behavior at high pressures and low temperatures
Polarity and size of particles
Also affect how a gas behaves

34. Gas Stoichiometry
When gases react, the coefficients in the balanced chemical equation represents both molar amounts and relative volumes
2H2(g) + 2O2(g)  2H2O(g)

35. Volume – Volume problems
What volume of oxygen gas is needed for the complete combustion of 4.00 L of methane gas?
CH4(g) + 2O2(g)  CO2(g) + 2H2O(g)

36. What volume of carbon dioxide gas can be made from 2.36 L of methane?

37. Volume – Mass problems
If 5.00 L of nitrogen reacts completely with hydrogen at a pressure of 3.00 atm and a temperature of 298 K, how much ammonia, in grams, is produced?
N2(g) + 3H2(g)  2NH3(g)

38. NH4NO3(s)  N2O(g) + 2H2O(g)
What mass of solid ammonium nitrate must be used to obtain L of dinitrogen oxide gas at STP?