Deck 10: Gases

Question 1

Which of the following statements about gases is false?

A)Gases are highly compressible.
B)Distances between molecules of gas are very large compared to bond distances within molecules.
C)Non-reacting gas mixtures are homogeneous.
D)Gases expand spontaneously to fill the container they are placed in.
E)All gases are colorless and odorless at room temperature.

Answer 1

All gases are colorless and odorless at room temperature.

Question 2

Which of the following equations shows an incorrect relationship between pressures given in terms of different units?

A)1.20 atm = 122 kPa
B)152 mm Hg = 2.03 × 10⁴ Pa
C)0.760 atm = 578 mm Hg
D)1.0 torr = 2.00 mm Hg
E)1.00 atm = 760 torr

Answer 2

1.0 torr = 2.00 mm Hg

Question 3

Of the following, ________ has a slight odor of bitter almonds and is toxic.

A)NH₃
B)N₂O
C)CO
D)CH₄
E)HCN

Answer 3

HCN

Question 4

Gaseous mixtures ________.

A)can only contain molecules
B)are all heterogeneous
C)can only contain isolated atoms
D)are all homogeneous
E)must contain both isolated atoms and molecules

Question 5

The first person to investigate the relationship between the pressure of a gas and its volume was ________.

A)Amadeo Avogadro
B)Lord Kelvin
C)Jacques Charles
D)Robert Boyle
E)Joseph Louis Gay-Lussac

Question 6

Which statement about atmospheric pressure is false?

A)As air becomes thinner, its density decreases.
B)Air actually has weight.
C)With an increase in altitude, atmospheric pressure increases as well.
D)The warmer the air, the lower the atmospheric pressure.
E)Atmospheric pressure prevents water in lakes, rivers, and oceans from boiling away.

Question 7

In ideal gas equation calculations, expressing pressure in Pascals (Pa), necessitates the use of the gas constant, R, equal to ________.

A)0.08206 atm L mol^-1K^-1
B)8.314 -Pa/mol-K
C)62.36 L torr mol^-1K^-1
D)1.987 cal mol^-1K^-1
E)none of the above

Question 8

The pressure exerted by a column of liquid is equal to the product of the height of the column times the gravitational constant times the density of the liquid, P = ghd. How high a column of water (d = 1.0 g/mL)would be supported by a pressure that supports a 713 mm column of mercury (d = 13.6 g/mL)?

A)14 mm
B)52 mm
C)713 mm
D)1.2 × 10⁴ mm
E)9.7 × 10³ mm

Question 9

One significant difference between gases and liquids is that ________.

A)a gas is made up of molecules
B)a gas expands to fill its container
C)a gas may consist of both elements and compounds
D)gases are always mixtures
E)All of the above answers are correct.

Question 10

Which one of the following is a valid statement of Avogadro's law?

A) = constant
B) = constant
C)PV = constant
D)V = constant × n
E)V = constant × P

Question 11

The pressure exerted by a column of liquid is equal to the product of the height of the column times the gravitational constant times the density of the liquid, P = ghd. How high a column of methanol (d = 0.79 g/mL)would be supported by a pressure that supports a 713 mm column of mercury
(d = 13.6 g/mL)?

A)713 mm
B)41 mm
C)1.2 × 10⁴ mm
D)9.7 × 10³ mm
E)17 mm

Question 12

Of the following, ________ has the odor of rotten eggs.

A)NH₃
B)H₂S
C)CO
D)NO₂
E)HCN

Question 13

Standard temperature and pressure (STP), in the context of gases, refers to ________.

A)298.15 K and 1 atm
B)273.15 K and 1 atm
C)298.15 K and 1 torr
D)273.15 K and 1 pascal
E)273.15 K and 1 torr

Question 14

Sodium bicarbonate is reacted with concentrated hydrochloric acid at 37.0 °C and 1.00 atm. The reaction of 6.00 kg of bicarbonate with excess hydrochloric acid under these conditions will produce ________ L of CO₂.

A)1.09 × 10²
B)2.85 × 10⁴
C)1.82 × 10⁴
D)8.70 × 10²
E)1.82 × 10³

Question 15

Of the following, ________ is a correct statement of Boyle's law.

A)PV = constant
B) = constant
C) = constant
D) = constant
E) = constant

Question 16

Of the following, only ________ is impossible for an ideal gas.

A) =
B) =
C) =
D) =
E) = = 0

Question 17

Of the following, ________ is a valid statement of Charles' law.

A) = constant
B) = constant
C)PV = constant
D)V = constant × n
E)V = constant × P

Question 18

The volume of an ideal gas is zero at ________.

A)0 °C
B)-45 °F
C)-273 K
D)-363 K
E)-273 °C

Question 19

"Isothermal" means ________.

A)at constant pressure
B)at constant temperature
C)at variable temperature and pressure conditions
D)at ideal temperature and pressure conditions
E)that ΔH_rxn = 0

Question 20

The molar volume of a gas at STP is ________ L.

A)0.08206
B)62.36
C)1.00
D)22.4
E)14.7

Question 21

The volume of a sample of gas (2.49 g)was 752 mL at 1.98 atm and 62 °C. The gas is ________.

A)SO₂
B)SO₃
C)NH₃
D)NO₂
E)Ne

Question 22

Sodium bicarbonate is reacted with concentrated hydrochloric acid at 25.0 °C and 1.50 atm. The reaction of 7.75 kg of bicarbonate with excess hydrochloric acid under these conditions will produce ________ L of CO₂.

A)1.82 × 10³
B)2.85 × 10⁴
C)1.82 × 10⁴
D)1.50 × 10³
E)8.70 × 10²

Question 23

Arrange the following gases in order of increasing average molecular speed at 25 °C. He, O₂, CO₂, N₂

A)He < N₂ < O₂ < CO₂
B)He < O₂ < N₂ < CO₂
C)CO₂ < O₂ < N₂ < He
D)CO₂ < N₂ < O₂ < He
E)CO₂ < He < N₂ < O₂

Question 24

The density of NO₂ in a 4.50 L tank at 760.0 torr and 25.0 °C is ________ g/L.

A)1.64
B)9.30
C)1.68
D)1.88
E)3.27

Question 25

The average kinetic energy of the particles of a gas is directly proportional to ________.

A)the rms speed
B)the square of the rms speed
C)the square root of the rms speed
D)the square of the particle mass
E)the particle mass

Question 26

According to kinetic-molecular theory, if the temperature of a gas is raised from 100 °C to 200 °C, the average kinetic energy of the gas will ________.

A)double
B)increase by a factor of 1.27
C)increase by a factor of 100
D)decrease by half
E)decrease by a factor of 100

Question 27

A sample of oxygen gas (O₂)was found to effuse at a rate equal to three times that of an unknown gas. The molecular weight of the unknown gas is ________ g/mol.

A)288
B)96
C)55
D)4
E)10.7

Question 28

A tank containing both HF and HBr gases developed a leak. The ratio of the rate of effusion of HF to the rate of effusion of HBr is ________.

A)4.04
B)0.247
C)2.01
D)0.497
E)16.3

Question 29

A sample of oxygen gas was found to effuse at a rate equal to two times that of an unknown gas. The molecular weight of the unknown gas is ________ g/mol.

A)64
B)128
C)8
D)16
E)8.0

Question 30

The kinetic-molecular theory predicts that pressure rises as the temperature of a gas increases because ________.

A)the average kinetic energy of the gas molecules decreases
B)the gas molecules collide more frequently with the wall
C)the gas molecules collide less frequently with the wall
D)the gas molecules collide more energetically with the wall
E)both the gas molecules collide more frequently with the wall and the gas molecules collide more energetically with the wall

Question 31

Which one of the following gases would have the highest average molecular speed at 25 °C?

A)O₂
B)N₂
C)CO₂
D)CH₄
E)SF₆

Question 32

According to kinetic-molecular theory, in which of the following gases will the root-mean-square speed of the molecules be the highest at 200 °C?

A)HCl
B)Cl₂
C)H₂O
D)SF₆
E)None. The molecules of all gases have the same root-mean-square speed at any given temperature.

Question 33

Which of the following is not part of the kinetic-molecular theory?

A)Atoms are neither created nor destroyed by ordinary chemical reactions.
B)Attractive and repulsive forces between gas molecules are negligible.
C)Gases consist of molecules in continuous, random motion.
D)Collisions between gas molecules do not result in the loss of energy.
E)The volume occupied by all of the gas molecules in a container is negligible compared to the volume of the container.

Question 34

A sample of an unknown volatile liquid was injected into a Dumas flask m_flask = 27.0928 g, v_flask = 0.1040 L)and heated until no visible traces of the liquid could be found. The flask and its contents were then rapidly cooled and reweighed (m_{flask + vapor} = 27.4593 g). The atmospheric pressure and temperature during the experiment were 0.976 atm and 18.0 °C, respectively. The unknown volatile liquid was ________.

A)C₆H₁₂
B)C₆H₁₄
C)C₇H₁₄
D)C₇H₁₆
E)C₆H₆

Question 35

Arrange the following gases in order of increasing average molecular speed at 25 °C. Cl₂, O₂, F₂, N₂

A)Cl₂ < F₂ < O₂ < N₂
B)Cl₂ < O₂ < F₂ < N₂
C)N₂ < F₂ < Cl₂ < O₂
D)Cl₂ < F₂ < N₂ < O₂
E)F₂ < O₂ < N₂ < Cl₂

Question 36

Of the following gases, ________ will have the greatest rate of effusion at a given temperature.

A)NH₃
B)CH₄
C)Ar
D)HBr
E)HCl

Question 37

A 255 mL round-bottom flask is weighed and found to have a mass of 114.85 g. A few milliliters of an easily vaporized liquid are added to the flask and the flask is immersed in a boiling water bath. All of the liquid vaporizes at the boiling temperature of water, filling the flask with vapor. When all of the liquid has vaporized, the flask is removed from the bath, cooled, dried, and reweighed. The new mass of the flask and the condensed vapor is 115.23 g. Which of the following compounds could the liquid be? (Assume the ambient pressure is 1 atm.)

A)C₄H₁₀
B)C₃H₇OH
C)C₂H₆
D)C₂H₅OH
E)C₄H₉OH

Question 38

At 333 K, which of the pairs of gases below would have the most nearly identical rates of effusion?

A)N₂O and NO₂
B)CO and N₂
C)N₂ and O₂
D)CO and CO₂
E)NO₂ and N₂O₄

Question 39

The density of air at STP is 1.285 g/L. Which of the following cannot be used to fill a balloon that will float in air at STP?

A)CH₄
B)NO
C)Ne
D)NH₃
E)HF

Question 40

At STP, the ratio of the root-mean-square speed of CO₂ to that of SO₂ is ________.

A)2.001
B)2.119
C)1.000
D)1.207
E)1.456

Question 41

A real gas will behave most like an ideal gas under conditions of ________.

A)high temperature and high pressure
B)high temperature and low pressure
C)low temperature and high pressure
D)low temperature and low pressure
E)STP

Question 42

A sample of a gas originally at 29 °C and 1.25 atm pressure in a 3.0 L container is allowed to contract until the volume is 2.2 L and the temperature is 11 °C. The final pressure of the gas is ________ atm.

A)2.9
B)2.8
C)1.6
D)2.1
E)0.38

Question 43

If 50.75 g of a gas occupies 10.0 L at STP, 129.3 g of the gas will occupy ________ L at STP.

A)3.92
B)50.8
C)12.9
D)25.5
E)5.08

Question 44

A sample of a gas (1.50 mol)is contained in a 15.0 L cylinder. The temperature is increased from 100 °C to 150 °C. The ratio of final pressure to initial pressure [ ] is ________.

A)1.50
B)0.667
C)0.882
D)1.13
E)1.00

Question 45

A gas at a pressure of 325 torr exerts a force of ________ N on an area of 5.5 m².

A)1.8 × 10³
B)59
C)2.4 × 10⁵
D)0.018
E)2.4

Question 46

A sample of a gas (5.0 mol)at 1.0 atm is expanded at constant temperature from 10 L to 15 L. The final pressure is ________ atm.

A)1.5
B)7.5
C)0.67
D)3.3
E)15

Question 47

A sample of a gas originally at 25 °C and 1.00 atm pressure in a 2.5 L container is subject to a pressure of 0.85 atm and a temperature of 15 °C. The final volume of the gas is ________ L.

A)3.0
B)2.8
C)2.6
D)2.1
E)0.38

Question 48

A gas vessel is attached to an open-end manometer containing a nonvolatile liquid of density 0.791 g/mL as shown below. The difference in heights of the liquid in the two sides of the manometer is 43.4 cm when the atmospheric pressure is 755 mm Hg. Given that the density of mercury is 13.6 g/mL, the pressure of the enclosed gas is ________ atm.

A)1.03
B)0.967
C)0.993
D)0.990
E)0.987

Question 49

A mixture of carbon dioxide and an unknown gas was allowed to effuse from a container. The carbon dioxide took 1.25 times as long to escape as the unknown gas. Which one could be the unknown gas?

A)Cl₂
B)CO
C)HCl
D)H₂
E)SO₂

Question 50

A gas at a pressure of 10.0 Pa exerts a force of ________ N on an area of 5.5 m².

A)55
B)0.55
C)5.5
D)1.8
E)18

Question 51

A mixture of two gases was allowed to effuse from a container. One of the gases escaped from the container 1.43 times as fast as the other one. The two gases could have been ________.

A)CO and SF₆
B)O₂ and Cl₂
C)CO and CO₂
D)Cl₂ and SF₆
E)O₂ and SF₆

Question 52

How much faster does ²³⁵UF₆ effuse than ²³⁸UF₆?

A)1.013 times as fast
B)1.009 times as fast
C)1.004 times as fast
D)1.006 times as fast
E)1.018 times as fast

Question 53

When gases are treated as real, via use of the van der Waals equation, the actual volume occupied by gas molecules ________ the pressure exerted and the attractive forces between gas molecules ________ the pressure exerted, as compared to an ideal gas.

A)decreases, increases
B)increases, increases
C)increases, decreases
D)does not affect, decreases
E)does not affect, increases

Question 54

An ideal gas differs from a real gas in that the molecules of an ideal gas ________.

A)have no attraction for one another
B)have appreciable molecular volumes
C)have a molecular weight of zero
D)have no kinetic energy
E)have an average molecular mass

Question 55

Which one of the following gases would deviate the least from ideal gas behavior?

A)Ne
B)CH₃Cl
C)Kr
D)CO₂
E)F₂

Question 56

A gas vessel is attached to an open-end manometer filled with a nonvolatile liquid of density 0.993 g/mL as shown below. The difference in heights of the liquid in the two sides of the manometer is 32.3 mm when the atmospheric pressure is 765 mm Hg. Given that the density of mercury is 13.6 g/mL, the pressure of the enclosed gas is ________ atm.

A)1.05
B)1.01
C)0.976
D)0.993
E)1.08

Question 57

A sample of H₂ gas (12.28 g)occupies 100.0 L at 400.0 K and 2.00 atm. A sample weighing 9.49 g occupies ________ L at 353 K and 2.00 atm.

A)109
B)68.2
C)54.7
D)147
E)77.3

Question 58

In a Torricelli barometer, a pressure of one atmosphere supports a 760 mm column of mercury. If the original tube containing the mercury is replaced with a tube having twice the diameter of the original, the height of the mercury column at one atmosphere pressure is ________ mm.

A)380
B)760
C)1.52 × 10³
D)4.78 × 10³
E)121

Question 59

Which noble gas is expected to show the largest deviations from the ideal gas behavior?

A)helium
B)neon
C)argon
D)krypton
E)xenon

Question 60

The van der Waals equation for real gases recognizes that ________.

A)gas particles have non-zero volumes and interact with each other
B)molar volumes of gases of different types are different
C)the non-zero volumes of gas particles effectively decrease the amount of "empty space" between them
D)the molecular attractions between particles of gas decreases the pressure exerted by the gas
E)all of the above statements are true

Question 61

The reaction of 50 mL of Cl₂ gas with 50 mL of CH₄ gas via the equation: Cl₂ (g) + CH₄ (g) → HCl (g) + CH₃Cl (g)
Will produce a total of ________ mL of products if pressure and temperature are kept constant.

A)100
B)50
C)200
D)150
E)250

Question 62

A 0.133 mol sample of gas in a 525 mL container has a pressure of 312 torr. The temperature of the gas is ________ °C.

A)20.3
B)-253
C)-20.3
D)203
E)22.4

Question 63

The molecular weight of a gas is ________ g/mol if 6.7 g of the gas occupies 6.3 L at STP.

A)24
B)3.6 × 10³
C)27
D)3.0 × 10²
E)1.8 × 10^-2

Question 64

The pressure of a sample of CH₄ gas (6.022 g)in a 30.0 L vessel at 402 K is ________ atm.

A)2.42
B)6.62
C)0.413
D)12.4
E)22.4

Question 65

The density of N₂O at 1.53 atm and 45.2 °C is ________ g/L.

A)18.2
B)1.76
C)0.388
D)9.99
E)2.58

Question 66

The amount of gas that occupies 36.52 L at 68.0 °C and 672 mm Hg is ________ mol.

A)127
B)1.15
C)878
D)24.4
E)12.7

Question 67

The reaction of 25 mL of N₂ gas with 75 mL of H₂ gas to form ammonia via the equation: N₂ (g) + 3H₂ (g) → 2NH₃ (g)
Will produce ________ mL of ammonia if pressure and temperature are kept constant.

A)250
B)50
C)200
D)150
E)100

Question 68

The amount of gas that occupies 60.82 L at 31.0 °C and 367 mm Hg is ________ mol.

A)1.18
B)0.850
C)894
D)11.6
E)0.120

Question 69

The reaction of 50 mL of Cl₂ gas with 50 mL of C₂H₄ gas via the equation: Cl₂ (g) + C₂H₄ (g) → C₂H₄Cl₂ (g)
Will produce a total of ________ mL of products if pressure and temperature are kept constant.

A)100
B)50
C)25
D)125
E)150

Question 70

The volume of 0.25 mol of a gas at 72.7 kPa and 15 °C is ________ m³.

A)8.1 × 10^-5
B)1.2 × 10^-4
C)4.3 × 10^-4
D)8.2 × 10^-3
E)2.2 × 10^-1

Question 71

The molecular weight of a gas is ________ g/mol if 3.5 g of the gas occupies 2.1 L at STP.

A)41
B)5.5 × 10³
C)37
D)4.6 × 10²
E)2.7 × 10^-2

Question 72

The reaction of 100 mL of Cl₂ gas with 100 mL of CH₄ gas via the equation: Cl₂ (g) + CH₄ (g) → HCl (g) + CH₃Cl (g)
Will produce a total of ________ mL of products if pressure and temperature are kept constant.

A)100
B)50
C)200
D)150
E)250

Question 73

The mass of nitrogen dioxide contained in a 4.32 L vessel at 48 °C and 141600 Pa is ________ g.

A)5.35 × 10⁴
B)53.5
C)10.5
D)70.5
E)9.46 × 10^-2

Question 74

A gas in a 325 mL container has a pressure of 695 torr at 19 °C. There are ________ mol of gas in the flask.

A)1.24 × 10^-2
B)1.48 × 10^-2
C)9.42
D)12.4
E)80.6

Question 75

The molecular weight of a gas that has a density of 7.10 g/L at 25.0 °C and 1.00 atm pressure is ________ g/mol.

A)174
B)14.6
C)28.0
D)5.75 × 10^-3
E)6.85 × 10^-2

Question 76

The molecular weight of a gas that has a density of 6.70 g/L at STP is ________ g/mol.

A)4.96 × 10²
B)1.50 × 10²
C)7.30 × 10¹
D)3.35
E)2.98 × 10^-1

Question 77

The density of ammonia gas in a 4.32 L container at 837 torr and 45.0 °C is ________ g/L.

A)3.86
B)0.719
C)0.432
D)0.194
E)4.22 × 10^-2

Question 78

The reaction of 50 mL of N₂ gas with 150 mL of H₂ gas to form ammonia via the equation: N₂ (g) + 3H₂ (g) → 2NH₃ (g)
Will produce ________ mL of ammonia if pressure and temperature are kept constant.

A)250
B)50
C)200
D)150
E)100

Question 79

The temperature of a sample of CH₄ gas (10.34 g)in a 50.0 L vessel at 1.33 atm is ________ °C.

A)984
B)-195
C)195
D)1260
E)-1260

Question 80

The molecular weight of a gas that has a density of 5.75 g/L at STP is ________ g/mol.

A)3.90
B)129
C)141
D)578
E)1.73 × 10^-3