Gases

1. Outline • Properties of Gases • Pressure • Gas Laws • Boyle’s Law • Charles’ Law • Avogadro’s Law • Ideal Gas Law • Dalton’s Law • Gas Stoichiometry • Kinetic Molecular Theory • Graham’s Law • Real Gases Gases Chapter 5

2. How do gases create pressure?

10. Boyle’s Law

16. Chapter 5: Examples – Gas Laws • What is the volume of 1.00 moles of an ideal gas at STP?

17. Molar Volume Tro: Chemistry: A Molecular Approach, 2/e

19. How does molar mass affect gas density?

20. How does temperature affect gas density?

21. Chapter 5: Examples – Gas Laws • In an industrial process, 500. L of hydrogen gas initially at 101 kPa and 22 ˚C is compressed into a vessel of volume 15.0 L and heated to 420 ˚C. What is it’s final pressure?

22. Chapter 5: Examples – Gas Laws • The volatile organic compound geraniol, a component of oil of roses, is used in perfumery. The density of the vapor at 260 ˚C is 0.480 g/L, when the pressure is 103 torr. What is the molar mass of geraniol?

23. Chapter 5: Examples – Gas Laws • A 32.5 mole sample of a gas is injected into an evacuated, constant-volume container at 22 ˚C and atmospheric pressure. What amount of moles of gas must be released, if the temperature is raised to 212 °C at constant pressure and some of the gas is allowed to escape during the heating?

24. Collecting Gas by Water Displacement Tro: Chemistry: A Molecular Approach, 2/e

26. Chapter 5: Examples – Gas Laws • Automobile air bags are filled when sodium azide, NaN3, decomposes into elemental sodium and nitrogen gas. If 10.0 g of sodium azide decompose, the nitrogen gas is collected over water at 18 ˚C (vapor pressure of water at 18 ˚C is 15.5 torr) and the barometric pressure is 747 mmHg. What is the partial pressure of dry nitrogen gas in the sample?

27. Chapter 5: Examples – Gas Laws • Haloethane, C2HBrClF3, is a nonflammable, nonexplosive, nonirritating gas that is commonly used as an inhaled anesthetic. If 15.0 g haloethane vapor is mixed with 23.5 g of oxygen gas, and the total pressure of the mixture is 855 mmHg, what is the mole fraction and partial pressure of each gas?

28. Chapter 5: Examples – Gas Laws • A mixture of argon and nitrogen gases has a density of 1.413 g/L at STP. What is the mole fraction of each gas?

29. Chapter 5: Examples – Gas Stoichiometry • Calculate the volume of acetylene, C2H2, produced at 25 ˚C and 1.00 atm when 10.0 g of calcium carbide reacts completely with water in the unbalanced reaction: CaC2(s) + H2O (l) → Ca(OH)2 (aq) + C2H2 (g)

30. Chapter 5: Examples – Gas Stoichiometry • What mass of titanium(IV) oxide is produced from the reaction of 200. L of titanium(IV) chloride and excess water at 500 kPa and 30 ˚C? Given the unbalanced equation: TiCl4 (g) + H2O (l) → TiO2 (g) + HCl (g)

31. Chapter 5: Examples – Gas Stoichiometry • If you have 355 L of hydrogen gas at 25 ˚C and 542 mmHg and combine it with excess nitrogen gas in the presence of an iron catalysis at 500 ˚C, what volume of ammonia gas will be collected under the same conditions?

32. Chapter 5: Examples – Gas Stoichiometry • A mixture of carbon monoxide and oxygen gas in a 2.89 L container at 907 K has a total pressure of 2.75 atm. After time, the pressure falls to 2.24 atm due to carbon dioxide formation. How many grams of carbon dioxide are formed?

33. Chapter 5: Examples – Gas Stoichiometry • Dichlorine monoxide is a powerful oxidizing agent that is used to bleach wood pulp and to treat municipal water supplies. It is made by the reaction: SO2 (g) + 2 Cl2 (g) → SOCl2 (g) + Cl2O (g) If you put sulfur dioxide in a flask at 125 mmHg at 22 ˚C, and add chlorine gas to this same flask, what should the chlorine gas partial pressure be in order to have the correct stoichiometric ratio of sulfur dioxide to chlorine gases?

34. Chapter 5: Examples – Gas Stoichiometry • A 3.0 L bulb containing helium gas at 145 mmHg is connected to a 2.0 L bulb containing argon gas at 355 mmHg by a valve. Calculate the partial pressure after the valve between the flasks is opened.

35. Maxwell-Boltmann DistributionEffect of Temperature on the Velocity of a Gas

36. Effect of Molar Mass on Molecular Speed Tro: Chemistry: A Molecular Approach, 2/e

37. Chapter 5: Examples – Gas Speed • Calculate the rms speed of oxygen molecules at 25 ˚C.

38. Chapter 5: Examples – Gas Density The four most common gases in the atmosphere are N2, O2, Ar, and CO2. Assuming all gases are in containers of equal size, temperature, and pressure, which gas has the highest density? • All have the same density • N2 • O2 • Ar • CO2

39. Chapter 5: Examples – Gas Density The four most common gases in the atmosphere are N2, O2, Ar, and CO2. Assuming all gases are in containers of equal size, temperature, and pressure, which gas has the highest density? • All have the same density • N2 • O2 • Ar • CO2

40. Mean Free Path Tro: Chemistry: A Molecular Approach, 2/e

41. Effusion Tro: Chemistry: A Molecular Approach, 2/e

42. Chapter 5: Examples – Gas Effusion • Why does it take several minutes for a reaction to occur between ammonia and hydrogen chloride gases in the same tube? Each gas is added to the opposite end of a tube and the tube is then sealed with cotton plugs. NH3 (g) + HCl (g)  NH4Cl (s)

43. Chapter 5: Examples – Gas Effusion • A sample of pure methane, CH4, is found to effuse through a porous barrier in 1.50 minutes. Under the same conditions an equal number of molecules of gas X effuse through the barrier in 4.73 minutes. What is the molar mass of gas X?

46. How does the ideal gas law change for a real gas?

48. Chapter 5: Examples – Real Gases Under what conditions would Cl2 gas be the least ideal? • High pressure and low temperature • High pressure and high temperature • Low pressure and high temperature • Low pressure and low temperature

49. Chapter 5: Examples – Real Gases Under what conditions would Cl2 gas be the least ideal? • High pressure and low temperature • High pressure and high temperature • Low pressure and high temperature • Low pressure and low temperature