Chapter 05 – Gases
39. Calculate the density, in g/L, of SF6 gas at 27C and 0.500 atm pressure.
40. Calculate the density, in g/L, of chlorine (Cl2) gas at STP.
Chapter 05 – Gases
41. Calculate the density of Ar(g) at –11C and 675 mmHg.
42. Which of these gases will have the greatest density at the same specified temperature and
pressure?
Chapter 05 – Gases
43. Which one of these gases is “lighter-than-air”?
44. Determine the molar mass of chloroform gas if a sample weighing 0.389 g is collected in a
flask with a volume of 102 cm3 at 97C. The pressure of the chloroform is 728 mmHg.
Chapter 05 – Gases
45. What is the molar mass of Freon-11 gas if its density is 6.13 g/L at STP?
46. Determine the molar mass of Freon-11 gas if a sample weighing 0.597 g occupies 100.
cm3 at 95C, and 1,000. mmHg.
Chapter 05 – Gases
47. 1.018 g of Freon-113 gas is trapped in a 145 mL container at 760. mmHg and 50.0C.
What is the molar mass of Freon-113?
48. A 0.271 g sample of an unknown vapor occupies 294 mL at 140.C and 847 mmHg. The
empirical formula of the compound is CH2. What is the molecular formula of the compound?
Chapter 05 – Gases
49. A 1.17 g sample of an alkane hydrocarbon gas occupies a volume of 674 mL at 28C and
741 mmHg. Alkanes are known to have the general formula CnH2n+2. What is the molecular
formula of the gas in this sample? (R = 0.08206 Latm/Kmol)
50. A 1.07 g sample of a Noble gas occupies a volume of 363 mL at 35C and 678 mmHg.
Identify the Noble gas in this sample. (R = 0.08206 Latm/Kmol)
Chapter 05 – Gases
51. A 707 mg sample of a gas containing only carbon and oxygen occupies a volume of 452
mL at 63C and 745 mmHg. Identify the gas in the sample. (R = 0.08206 Latm/Kmol)
52. A 792 mg sample of a gas containing only sulfur and oxygen occupies a volume of 372
mL at 54C and 678 mmHg. Identify the gas in the sample. (R = 0.08206 Latm/Kmol)
Chapter 05 – Gases
53. A gaseous compound is 30.4% nitrogen and 69.6% oxygen by mass. A 5.25-g sample of
the gas occupies a volume of 1.00 L and exerts a pressure of 1.26 atm at –4.0C. Which of
these choices is its molecular formula?
54. A mixture of three gases has a total pressure of 1,380 mmHg at 298 K. The mixture is
analyzed and is found to contain 1.27 mol CO2, 3.04 mol CO, and 1.50 mol Ar. What is the
partial pressure of Ar?
55. A sample of hydrogen gas was collected over water at 21C and 685 mmHg. The volume
of the container was 7.80 L. Calculate the mass of H2(g) collected. (Vapor pressure of water =
18.6 mmHg at 21C.)
56. A sample of carbon monoxide gas was collected in a 2.0 L flask by displacing water at
28C and 810 mmHg. Calculate the number of CO molecules in the flask. The vapor pressure
of water at 28C is 28.3 mmHg.
Chapter 05 – Gases
57. Air contains 78% N2, 21% O2, and 1% Ar, by volume. What is the density of air at 1,000.
torr and –10C?
58.
What volume of sulfur dioxide gas at 45C and 723 mmHg will react completely with 0.870 L of oxygen gas at constant
temperature and pressure?
2 SO2(g) + O2(g) → 2SO3(g)
Chapter 05 – Gases
59.
2.0 L of gas A at 1.0 atm and 1.0 L of gas B at 1.0 atm are combined in a 3.0 L flask. The flask is sealed and over time they
react completely to give gas C according to the following chemical equation:
2A(g) + B(g) →C(g)
Assuming the temperature stays constant, what will be the pressure after the reaction goes to completion?
60.
Gas A and gas B are combined in a flask at initial pressures of 1.0 atm each. The flask is sealed and over time they react to
completion to give gas C according to the following chemical equation:
2A(g) + B(g) → C(g)
Assuming the temperature stays constant, what will be the total pressure in the flask after the reaction goes to completion?
Chapter 05 – Gases
61.
What volume of O2(g) at 810. mmHg pressure is required to react completely with a 4.50g sample of C(s) at 48C?
2 C(s) + O2(g) → 2 CO(g)
62.
How many liters of chlorine gas at 25C and 0.950 atm can be produced by the reaction of 12.0 g of MnO2 with excess
HCl(aq) according to the following chemical equation?
MnO2(s) + 4HCl(aq) → MnCl2(aq) + 2H2O(l) + Cl2(g)
Chapter 05 – Gases
63. How many liters of oxygen gas at 153C and 0.820 atm can be produced by the
decomposition of 22.4 g of solid KClO3? (The other decomposition product is solid potassium
chloride.)
64. When active metals such as magnesium are immersed in acid solution, hydrogen gas is
evolved. Calculate the volume of H2(g) at 30.1C and 0.85 atm that can be formed when 275
mL of 0.725 M HCl solution reacts with excess Mg to give hydrogen gas and aqueous
magnesium chloride.
Chapter 05 – Gases
65. Calculate the volume of H2(g) at 273 K and 2.00 atm that will be formed when 275 mL of
0.725 M HCl solution reacts with excess Mg to give hydrogen gas and aqueous magnesium
chloride.
66. What mass of KClO3 must be decomposed to produce 126 L of oxygen gas at 133C and
0.880 atm? (The other reaction product is solid KCl.)
Chapter 05 – Gases
67. Liquid nitrogen has a density of 0.807 g/mL at –195.8 C. If 1.00 L of N2(l) is allowed to
warm to 25C at a pressure of 1.00 atm, what volume will the gas occupy? (R = 0.08206
Latm/Kmol)
68. Which statement is false?
Chapter 05 – Gases
69. The molecules of different samples of an ideal gas have the same average kinetic energies,
at the same
70. If equal masses of O2(g) and HBr(g) are in separate containers of equal volume and
temperature, which one of these statements is true?
Chapter 05 – Gases
71. Which gas has molecules with the greatest average molecular speed at 25C?
72. Which of these gas molecules has the highest average kinetic energy at 25C?
73. Deviations from the ideal gas law are greater at
Chapter 05 – Gases
74. For a substance that remains a gas under the conditions listed, deviation from the ideal gas
law would be most pronounced at
Chapter 05 – Gases
75.
What is the pressure of the gas trapped in the apparatus shown below when the atmospheric pressure is 720 mmHg?
Chapter 05 – Gases
76.
Determine the pressure of the gas trapped in the apparatus shown below when the atmospheric pressure is 695 mmHg.