Deck 6: Properties of Gases: the Air We Breathe

Question 1

Which of the following graphs shows the correct relationship between the temperature and volume of an ideal gas at a given pressure? Note the origin corresponds to V = 0 and T = 0.

A)
B)
C)
D)

Answer 1

Question 2

A barometer measures a pressure of 745 mm Hg. What is this pressure in atm?

A) 0.980 atm
B) 1.02 atm
C) 1.03 * 10⁵ atm
D) 1.00 * 10⁴ atm
E) 0.556 atm

Answer 2

0.980 atm

Question 3

What is the volume of a gas that exerts a pressure of 457 mm Hg if it exerted a pressure of 2.50 atm when its volume was 25.0 mL?

A) 9.62 mL
B) 1.80 L
C) 0.104 L
D) 6.01 mL
E) 25.0 L

Answer 3

0.104 L

Question 4

What force is exerted by exactly one atmosphere of pressure (1.013* 10⁵ Pa) on a mercury barometer with an inner diameter of 20.00 mm? Recall that the area of a circle is A = $\pi$ r² and that 1 N = 1 kg m/s².

A) 31.82 N
B) 15.91 N
C) 127.3 N
D) 3.182 * 10⁷ N
E) 40.52 N

Question 5

The atmospheric pressure is reported to be 31.5 in of mercury. The prevailing weather system on this day would be classified as __________

A) a cold front.
B) a warm front.
C) low pressure.
D) high pressure.
E) normal.

Question 6

If the pressure in the eye of a hurricane is 645 mbar, what is the corresponding pressure in mm Hg? Recall 1.013 bar = 1 atm.

A) 637 mm Hg
B) 0.637 mm Hg
C) 484 mm Hg
D) 497 mm Hg
E) 645 mm Hg

Question 7

Which of the following graphs shows the correct relationship between the pressure and temperature of an ideal gas in a given volume? Note the origin corresponds to P = 0 and T = 0.

A)
B)
C)
D)

Question 8

What height of water (in meters) is necessary to measure a pressure of 760 mm Hg? The density of mercury is 13.79 g/cm³, and the density of water is 1.00 g/cm³.

A) 0.760 m
B) 1.05 * 10⁴ m
C) 0.105 m
D) 10.5 m
E) 55.1 mm

Question 9

The pressure of a gas is inversely proportional to __________

A) the volume of the gas.
B) the number of gas particles.
C) the temperature of the gas.
D) the molar mass of the gas.
E) the mass of the gas.

Question 10

Which of the following substances will require the highest column for measuring an atmospheric pressure of 0.950 atm? (Assume all the barometers have columns with the same diameter.)

A) Mercury (d = 13.59 g/cm³)
B) Ethanol (d = 0.79 g/cm³)
C) Ethylene glycol (d = 1.09 g/cm³)
D) Water (d = 1.00 g/cm³)
E) Carbon tetrachloride (d = 1.58 g/cm³)

Question 11

What pressure (in Pa) will be exerted on the bottom of a 63.5 kg hiker's foot when she stands on a rusty nail? Assume the diameter of the tip of the nail is 1.00 mm. The acceleration due to gravity is 9.81 m/s². Recall that the area of a circle is: A = $\pi$ r² and that 1 Pa = 1 kg m^-1 s^-2.

A) 1.98 * 10² Pa
B) 7.93 * 10² Pa
C) 1.98 * 10⁸ Pa
D) 7.93 *10⁸ Pa
E) 7.93 * 10⁵ Pa

Question 12

What pressure will be measured (in Pa) if a gas is exerting a force of 10.00 N on a mercury barometer with an inner diameter of 10.00 mm? Recall that the area of a circle is A = $\pi$ r² and that 1 N = 1 kg m/s².

A) 3.183 * 10⁴ Pa
B) 1.273 *10⁵ Pa
C) 3.183* 10^-2 Pa
D) 1.273*10^-2 Pa

Question 13

A balloon is filled with 3.00 L of helium at a pressure of 765 torr. What is the volume of the balloon at an altitude where the pressure in the balloon is 530 torr?

A) 0.231 L
B) 4.33 L
C) 2.08 L
D) 1.00 L
E) 3.00 L

Question 14

A sample of gas at 4.0 atm and 25.0 mL is heated from 25°C to 40°C. If the pressure remains constant, what is the final volume of the gas?

A) 26.2 mL
B) 40.0 mL
C) 23.8 mL
D) 105 mL
E) 25.0 mL

Question 15

The atmospheric pressure in the eye of a hurricane is found to be 26.6 in of mercury. The pressure in the eye of this hurricane is __________

A) 760 mm Hg.
B) 1.00 *10⁵ Pa.
C) 0.889 atm.
D) 0.987 bar.
E) 0.785 atm.

Question 16

Two identical cement blocks are placed on a glass table in different positions as shown in the diagram. Which statement about these blocks is correct?

A) A exerts more pressure on the table.
B) B exerts more pressure on the table.
C) Both blocks exert the same pressure on the table.
D) A exerts more force on the table.
E) B exerts more force on the table.

Question 17

Which of the following graphs shows the correct relationship between pressure and volume for n moles of gas at temperature T?

A)
B)
C)
D)

Question 18

A gas, initially at 1.00 atm and 5.00 L, is compressed to a pressure of 15.00 atm. What is the volume of the gas at this pressure?

A) 3.00 L
B) 333 mL
C) 0.333 mL
D) 3.00 mL
E) 5.00 L

Question 19

What is the pressure in the gas bulb connected to the mercury manometer shown in the diagram if the ambient pressure is 750 torr? The heights labeled in the diagram are 15 mm and 21 mm.

A) 756 torr
B) 771 torr
C) 729 torr
D) 765 torr
E) 735 torr

Question 20

The cold inflation pressure of many car tires is 30 lb/in², which is the gauge pressure. If 1 atm = 14.7 lb/in², what is the gauge pressure of a car tire in torr?

A) 2.04 torr
B) 1.55*10³ torr
C) 441 torr
D) 0.580 torr
E) 1.12* 10⁴ torr

Question 21

Which one of these samples contains the smallest number of molecules?

A) 1.0 L of H₂ at STP (0°C and 1atm)
B) 1.0 L of N₂ at STP
C) 1.0 L of H₂ at 20°C and 760 torr
D) 1.0 L of N₂ at 0°C and 800 torr
E) 1.0 L of He at STP

Question 22

Which of the following samples of an ideal gas has the lowest density?

A)
B)
C)
D)

Question 23

Calcium carbonate (100.1 g/mol) decomposes according to the following reaction equation: CaCO₃(s) $\rightarrow$ CaO(s) + CO₂(g)
What pressure of CO₂ gas will form in a 25.0 mL jar containing 5.00 g CaCO₃ at 300 K if 0.00500% of the solid decomposes?

A) 0.246 atm
B) 2.46 atm
C) 1.00 atm
D) 2.46 *10³ atm
E) 2.46 * 10^-3 atm

Question 24

Which of the gases shown here will exert the lowest pressure, assuming that each container has the same volume and temperature?

A)
B)
C)
D)

Question 25

The density of a pure gas at STP depends on its __________

A) molar mass.
B) concentration.
C) temperature.
D) volume.
E) pressure.

Question 26

A 1.50 mol sample of He occupies a volume of 2.50 L at a pressure of 14.7 atm. What will be the pressure of a 1.50 mol sample of H₂ gas under the same conditions?

A) 7.33 atm
B) 14.7 atm
C) 29.4 atm
D) 1.00 atm
E) 24.5 atm

Question 27

In an experiment, 7.5 mol of a gas are held in a 3.5 L container at 39°C. What pressure does the gas exert if it is assumed to be ideal?

A) 5.5 * 10³ atm
B) 2.9 * 10⁴ atm
C) 6.9 atm
D) 55 atm
E) 96 atm

Question 28

What is the pressure of a 3.5 mmol sample of ethane (C₂H₆) gas contained in a 0.500 L flask at 298 K?

A) 171 mm Hg
B) 1.30 *10⁵ mm Hg
C) 130 mm Hg
D) 326 mm Hg
E) 17.1 mm Hg

Question 29

Which of the following reactions will result in a reduced total pressure?

A) CH₄(g) + 2O₂(g) $\rightarrow$ CO₂(g) + 2H₂O(g)
B) 2N₂O(g) $\rightarrow$ 2N₂(g) + O₂(g)
C) 2HI(g) $\rightarrow$ H₂(g) + I₂(g)
D) 2H₂(g) + O₂(g) $\rightarrow$ 2H₂O( )

Question 30

What is the temperature if 5.0 g of methane (CH₄) in a 100.0 mL container exerts a pressure of 42 atm?

A) -110°C
B) +164°C
C) -270°C
D) -263°C
E) +263°C

Question 31

What volume is occupied by 1.00 mol of an ideal gas at 1.00 atm and 0.00°C?

A) 22.4 L
B) 22.7 L
C) 22.1 L
D) 15.0 L
E) 27.2 L

Question 32

An unknown gas held in a 25.0 mL flask at 45°F exerts a pressure of 25 mtorr. By using this information with the ideal gas law, it is possible to determine __________

A) the mass of the gas in the container.
B) the identity of the gas in the container.
C) the number of molecules of the gas in the container.
D) the molecular geometry of the gas in the container.
E) nothing more about the gas.

Question 33

How many moles of propane are contained in a 5.00 L tank at 450 torr and 25°C?

A) 0.12 mol
B) 92 mol
C) 1.4 mol
D) 1100 mol
E) 41 mol

Question 34

The pressure gauge on a cylinder used to fill balloons with He shows a pressure of 1275 psi at a temperature of 25°C. Assuming the cylinder has a volume of 10 L, how many grams of He does the cylinder contain?

A) 520 g
B) 142 g
C) 6.70 * 10 ^-4 g
D) 37.0 g
E) 4.00 g

Question 35

Indicate the gas with the greatest density at STP.

A) CH₄
B) He
C) Ar
D) H₂
E) O₂

Question 36

In an experiment, 25.0 mL of a gas with a pressure of 1.00 atm is contained in a balloon at 25.0°C. The balloon is then cooled to 5.0°C, and the pressure is found to be 0.750 atm. What is the volume of the gas under the new conditions?

A) 17.5 mL
B) 20.1 mL
C) 25.0 mL
D) 31.1 mL
E) 35.7 mL

Question 37

What volume is occupied by 1.00 mol of an ideal gas at 1.00 bar and 0.00°C?

A) 22.4 L
B) 22.7 L
C) 22.1 L
D) 15.0 L
E) 27.2 L

Question 38

Which of the following is unimportant when using the ideal gas law?

A) The chemical identity of the gas sample.
B) The temperature of the gas sample.
C) The pressure of the gas sample.
D) The volume of the container holding the gas sample.
E) The amount of gas.

Question 39

Which of the gas samples shown below in identical containers has the lowest density (g/L)?

A)
B)
C)
D)

Question 40

Four containers, each with the same volume and at the same temperature, are shown in the following diagrams. Which container is at the highest pressure?

A)
B)
C)
D)

Question 41

What is the density of propane gas (CH₃CH₂CH₃, 44.1 g/mol) at 25°C and 650 mm Hg?

A) 1.54 g/L
B) 3.55 g/mL
C) 18.3 g/L
D) 2.05 g/L
E) 1.17 g/L

Question 42

The density of a gaseous compound of nitrogen and oxygen is 4.11 g/L at STP. What is the most likely formula of this gas?

A) N₂O₄
B) N₂O₅
C) N₂O
D) NO₂
E) NO

Question 43

In a mixture of hydrogen and helium gases, the mole fraction of helium is 0.750. If the partial pressure of hydrogen in the mixture is 75 torr, what is the total pressure of the mixture?

A) 100 torr
B) 300 torr
C) 19 torr
D) 750 torr
E) 760 torr

Question 44

Which container shown below has the largest partial pressure of helium? The white circles represent helium atoms; the dark circles represent argon atoms.

A)
B)
C)
D)

Question 45

Which container shown below has the largest partial pressure of argon? The white circles represent helium atoms; the dark circles represent argon atoms.

A)
B)
C)
D)

Question 46

The density of an unknown gas is 1.72 g/L at 750.0 torr and 30.0°C. Which of the following could be the unknown gas?

A) CS₂
B) NO
C) N₂O
D) NH₃
E) NO₂

Question 47

What is the molar mass of a gas that has a density of 2.62 g/L at 2.00 atm and 25.0°C?

A) 32.0 g/mol
B) 16.0 g/mol
C) 64.0 g/mol
D) 28.0 g/mol
E) 2.69 g/mol

Question 48

In which of the following containers is the mole fraction of helium greatest? The white circles represent helium atoms; the dark circles represent argon atoms.

A)
B)
C)
D)

Question 49

During the decomposition of CaCO₃(s) into CaO(s) and O₂(g), 100.0 mL of gas is collected by the displacement of water in a flask at 25°C with an atmospheric pressure of 755 mm Hg. The vapor pressure of water at this temperature is 23.8 mm Hg. What mass of oxygen was collected?

A) 0.679 mg
B) 21.7 mg
C) 12.9 mg
D) 0.807 mg
E) 126 mg

Question 50

The partial pressure of a gas is __________

A) the pressure the gas exerts when pure.
B) the same as the vapor pressure of the gas.
C) the pressure due to the gas in a mixture.
D) the total pressure of a mixture of gases.
E) the pressure exerted by one molecule of the gas.

Question 51

What is the mole fraction of H₂ in a mixture with a total pressure of 800 torr when the partial pressure of H₂ is 90 torr?

A) 0.11
B) 8.8
C) 1.0
D) 0.5
E) 0.88

Question 52

Nitrous oxide (N₂O, also known as laughing gas) has been used as an anesthetic. What is the density of N₂O at 750 torr and 30°C?

A) 1.2 g/L
B) 1.1 g/L
C) 1.8 g/L
D) 1.7 g/L
E) 1.5 g/L

Question 53

In which of the following containers is the mole fraction of argon greatest? The white circles represent helium atoms; the dark circles represent argon atoms.

A)
B)
C)
D)

Question 54

N₂O (laughing gas) is used as an anesthetic. A dentist has a 2.00 L flask of N₂O at a pressure of 1.00 atm and a 3.00 L flask of nitrogen gas at 2.00 atm that are separated by a valve. What is the pressure in the flasks when the valve is opened, and the gases mix together? Both flasks are at the same temperature, and the temperature does not change when the gases mix.

A) 3.00 atm
B) 1.50 atm
C) 1.60 atm
D) 1.20 atm
E) 1.00 atm

Question 55

Which of the following gases has nearly the same density as CO₂ at room temperature and atmospheric pressure?

A) N₂
B) O₂
C) N₂O
D) Ar
E) CO

Question 56

A mixture of cyclopropane gas (C₃H₆) and oxygen (O₂) in a 1.00 to 4.00 mole ratio is used as an anesthetic. What mass of cyclopropane gas is present in a 2.00 L flask at 23.5°C if the total pressure of the oxygen and propane is 1.00 atm? (The molar mass of C₃H₆ is 42.078 g/mol.)

A) 0.69 g
B) 3.45 g
C) 2.76 g
D) 6.83 mg
E) 8.73 g

Question 57

Which of the containers shown below has the lowest total pressure? The white circles represent helium atoms; the dark circles represent argon atoms.

A)
B)
C)
D)

Question 58

Which of the following graphs shows how the density of an ideal gas changes with temperature?

A)
B)
C)
D)

Question 59

A gas mixture has partial pressures of 120 torr N₂, 350 torr Ar, and 480 torr SF₆. What is the mole fraction of sulfur hexafluoride in the mixture?

A) 0.13
B) 0.37
C) 0.45
D) 0.51
E) 0.55

Question 60

Which one of the following gases could most easily be differentiated from propane (CH₃CH₂CH₃) on the basis of density when compared at the same temperature and pressure?

A) CO₂
B) N₂O
C) NO₂
D) F₂
E) CH₂
CH-CH₃

Question 61

What is the temperature of a sample of ozone (O₃) with an average kinetic energy of 1.73 kJ/mol?

A) 10 K
B) 270 K
C) 139 K
D) 280 K
E) 79 K

Question 62

What is the root-mean-square speed of N₂O at 25°C?

A) 13.0 m/s
B) 411 m/s
C) 127 m/s
D) 37.9 m/s
E) 18.6 m/s

Question 63

What is the average kinetic energy (in kJ/mol) of nitrous oxide (N₂O) molecules at 30.0°C?

A) 0.906 kJ/mol
B) 3.78 kJ/mol
C) 288 kJ/mol
D) 147 kJ/mol
E) 2.52 kJ/mol

Question 64

Which of these gases (Ar, N₂O, H₂) has the same average kinetic energy at 25°C as CO₂?

A) Ar
B) N₂O
C) H₂
D) They are all the same as CO₂.
E) They are all different from CO₂.

Question 65

Determine the root-mean-square speed of methane (CH₄) molecules that have an average kinetic energy of 10.5 J/mol.

A) 337 m/s
B) 1.14 m/s
C) 2.81 * 10¹³ m/s
D) 36.2 m/s
E) 1150 m/s

Question 66

_____ is how gases escape through a hole in a container, and _____ is how gases spread among each other.

A) Diffusion; effusion
B) Effusion; diffusion
C) Effusion; effusion
D) Diffusion; diffusion

Question 67

Which set of gases is listed from slowest to fastest diffusion rate?

A) HCN < H₂ < He < O₃
B) H₂ < He < HCN < O₃
C) O₃ < HCN < He < H₂
D) HCN < He < O₃ < H₂
E) H₂ < HCN < He < O₃

Question 68

Helium-neon (HeNe) lasers contain a low-pressure mixture of He and Ne gases. How much greater is the root-mean-square speed of He atoms than Ne atoms in a HeNe laser?

A) 5.0
B) 0.20
C) 2.2
D) 1.6
E) 0.45

Question 69

_____ is how gases spread among each other; and _____ is how gases escape through a hole in a container.

A) Diffusion; effusion
B) Effusion; diffusion
C) Effusion; effusion
D) Diffusion; diffusion

Question 70

Which set of gases is listed from fastest to slowest diffusion rate?

A) HCN > H₂ > He > O₃
B) H₂ > He > HCN > O₃
C) O₃ > HCN > He > H₂
D) HCN > He > O₃ > H₂
E) H₂ > HCN > He > O₃

Question 71

Which set of gases is listed from slowest to fastest effusion rate?

A) N₂O < NO₂ < NO < N₂O₄
B) NO < N₂O < NO₂ < N₂O₄
C) N₂O₄ < NO₂ < N₂O < NO
D) NO < NO₂ < N₂O < N₂O₄
E) N₂O₄ < N₂O < NO₂ < NO

Question 72

Which set of gases is listed from fastest to slowest effusion rate?

A) N₂O > NO₂ > NO > N₂O₄
B) NO > N₂O > NO₂ > N₂O₄
C) N₂O₄ > NO₂ > N₂O > NO
D) NO > NO₂ > N₂O > N₂O₄
E) N₂O₄ > N₂O > NO₂ > NO

Question 73

Which of the following gases will effuse through a hole in a balloon fastest?

A) Kr
B) NO
C) N₂O
D) NO₂
E) Ar

Question 74

Which set of gases is listed from lowest to highest root-mean-square speed at 25°C?

A) Kr < CO₂ < NO₂ < SF₆
B) SF₆ < NO₂ < CO₂ < Kr
C) SF₆ < Kr < CO₂ < NO₂
D) SF₆ < Kr < NO₂ < CO₂
E) CO₂ < NO₂ < Kr < SF₆

Question 75

The root-mean-square speed of a gas is found to be 391.2 m/s at 270 K. Which of the following is the gas?

A) N₂
B) O₂
C) Ar
D) CO₂
E) CO

Question 76

Which one of the following statements about the kinetic molecular theory is not correct?

A) The size of a molecule is negligible.
B) Gas molecules move constantly and randomly throughout the space they occupy.
C) The average kinetic energy of a gas molecule is directly proportional to the absolute temperature of the gas.
D) Collisions of gas molecules with each other and with the walls of the container are elastic.
E) Gas molecules attract and repel each other.

Question 77

Which set of gases is listed from highest to lowest root-mean-square speed at 25°C?

A) Kr > CO₂ > NO₂ > SF₆
B) SF₆ > NO₂ > CO₂ > Kr
C) SF₆ > Kr > CO₂ > NO₂
D) SF₆ > Kr > NO₂ > CO₂
E) CO₂ > NO₂ > Kr > SF₆

Question 78

The diffusion rate of H₂ in a lecture hall was found to be 25.0 m/sec at 25°C. How long will it take poisonous HCN gas to diffuse 10 m in the same room?

A) 1.5 s
B) 0.11 s
C) 5.4 s
D) 0.19 s
E) 2.7 s

Question 79

Which of the following figures is the most accurate representation of a gas sample? The arrows show the velocities of individual molecules.

A)
B)
C)
D)

Question 80

Which one of the following statements is not correct? In a sample of air at a given temperature ____________

A) the nitrogen and oxygen molecules have the same average kinetic energy.
B) the nitrogen and oxygen molecules have the same average speed.
C) some nitrogen molecules are moving slower than some oxygen molecules.
D) some nitrogen molecules are moving faster than some oxygen molecules.
E) all the molecules are moving.