Chapter 05 – Gases
77. 10.0 g of gaseous ammonia and 6.50 g of oxygen gas are introduced into a previously
evacuated 5.50 L vessel. If the ammonia and oxygen then react to yield NO gas and water
vapor, what is the final gas pressure inside the vessel at 23ºC?
78. 5.00 g of hydrogen gas and 50.0 g of oxygen gas are introduced into an otherwise empty
9.00 L steel cylinder, and the hydrogen is ignited by an electric spark. If the reaction product
is gaseous water and the temperature of the cylinder is maintained at 35ºC, what is the final
gas pressure inside the cylinder?
Chapter 05 – Gases
79. 9.45 g of liquid hexane (C6H14) is introduced into a 10.0 L vessel containing 13.15 atm of
oxygen gas at 21ºC and ignited, yielding carbon dioxide and water. If the vessel is then cooled
to –10.ºC, what will be the gas pressure inside the vessel?
80. 10.0 g of gaseous ammonia and 6.50 g of oxygen gas are introduced into a previously
evacuated 5.50 L vessel. If the ammonia and oxygen then react to yield NO gas and water
vapor, what is the final density of the gas mixture inside the vessel at 23ºC?
Chapter 05 – Gases
81. A method of removing CO2 from a spacecraft is to allow the CO2 to react with sodium
hydroxide. (The products of the reaction are sodium carbonate and water.) What volume of
carbon dioxide at 25C and 749 mmHg can be removed per kilogram of sodium hydroxide
that reacts?
82. A spacecraft is filled with 0.500 atm of N2 and 0.500 atm of O2. Suppose a micrometeor
strikes this spacecraft and puts a very small hole in its side. Under these circumstances,
Chapter 05 – Gases
83. A spacecraft is filled with 0.500 atm of O2 and 0.500 atm of He. If there is a very small
hole in the side of this craft such that gas is lost slowly into outer space,
84. 1.000 atm of dry nitrogen, placed in a container having a pinhole opening in its side, leaks
from the container 3.55 times faster than does 1.000 atm of an unknown gas placed in this
same apparatus. Which of these species could be the unknown gas?
Chapter 05 – Gases
85. 1.000 atm of oxygen gas, placed in a container having a pinhole opening in its side, leaks
from the container 2.14 times faster than does 1.000 atm of an unknown gas placed in this
same apparatus. Which of these species could be the unknown gas?
86. Samples of the following volatile liquids are opened simultaneously at one end of a room.
If you are standing at the opposite end of this room, which species would you smell first?
(Assume that your nose is equally sensitive to all these species.)
Chapter 05 – Gases
87. A sample of mercury(II) oxide is placed in a 5.00 L evacuated container and heated until it
decomposes entirely to mercury metal and oxygen gas. The container is then cooled to 25C.
One now finds that the gas pressure inside the container is 1.73 atm. What mass of
mercury(II) oxide was originally placed into the container?
88. The mole fraction of oxygen molecules in dry air is 0.2095. What volume of dry air at
1.00 atm and 25C is required for burning 1.00 L of hexane (C6H14, density = 0.660 g/mL)
completely, yielding carbon dioxide and water?
Chapter 05 – Gases
89. The mole fraction of oxygen molecules in dry air is 0.2095. What volume of dry air at
1.00 atm and 25C is required for burning 1.00 L of octane (C8H18, density = 0.7025 g/mL)
completely, yielding carbon dioxide and water?
90. A block of dry ice (solid CO2, density = 1.56 g/mL) of dimensions 25.0 cm 25.0 cm
25.0 cm is left to sublime (i.e. to pass from the solid phase to the gas phase) in a closed
chamber of dimensions 4.00 m 5.00 m 3.00 m. The partial pressure of carbon dioxide in
this chamber at 25C will be
Chapter 05 – Gases
91. A 2.50-L flask contains a mixture of methane (CH4) and propane (C3H8) at a pressure of
1.45 atm and 20C. When this gas mixture is then burned in excess oxygen, 8.60 g of carbon
dioxide is formed. (The other product is water.) What is the mole fraction of methane in the
original gas mixture?
92.
Select True or False: A “gas” is a substance in which the molecules are separated on the average by distances that are large
compared with the sizes of the molecules.
Chapter 05 – Gases
93. Select True or False: The standard temperature and standard pressure in units of C and
Chapter 05 – Gases
94.
What is the pressure (mmHg) of the sample of gas trapped in the open-tube mercury manometer shown below if atmospheric
pressure is 742 mmHg and h = 16.7 cm?
Chapter 05 – Gases
95.
What is the pressure (in atmospheres) of the sample of gas trapped in the open-tube mercury manometer shown below if
atmospheric pressure is 735 mmHg and h = 8.3 cm?
Chapter 05 – Gases
96.
What is the pressure (in atmospheres) of the sample of gas trapped in the closed-tube mercury manometer shown below if h =
23.6 cm?
Chapter 05 – Gases
97.
What is the pressure (mmHg) of the sample of gas trapped in the closed-tube mercury manometer shown below if
atmospheric pressure is 751 mmHg and h = 17.3 cm?
Chapter 05 – Gases
98. Select True or False: The magnitude of the van der Waals “a” constant reflects the
strength of the attractions between molecules of a given type of gas.
99. Select True or False: Boyle’s Law states that the volume of a fixed amount of gas
maintained at constant temperature is directly proportional to the gas pressure
100. Select True or False: Charles Law states that the volume of a fixed amount of gas
maintained at constant pressure is inversely proportional to the absolute temperature of the
Chapter 05 – Gases
101. Select True or False: Avogadro’s Law states that at constant pressure and temperature,
the volume of a gas is directly proportional to the number of moles of the gas present.
102. Select True or False: Dalton’s Law states that the total pressure of a mixture of gases is
just the sum of the pressures that each gas would exert if it were present alone.
103. How many grams of N2O, nitrous oxide, are contained in 500. mL of the gas at STP?