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) All gases are colorless and odorless at room temperature.
D) Non- reacting gas mixtures are homogeneous.
E) Gases expand spontaneously to fill the container they are placed in.

Answer 1

All gases are colorless and odorless at room temperature.

Question 2

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

Answer 2

128

Question 3

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

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

Answer 3

V = constant × n

Question 4

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

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

Question 5

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

Question 6

The density of krypton gas at 1.21 atm and 50.0 °C is g/L.

A) 0.295
B) 7.65
C) 0.0456
D) 3.82
E) 0.262

Question 7

If one was told that their blood pressure was 130/80, their systolic pressure was .

A) 130 mmHg
B) 80 Pa
C) 80 mmHg
D) 130 Pa
E) 80 psi

Question 8

Of the following, has the odor of rotting eggs.

A) NO₂
B) NH₃
C) CO
D) H₂S
E) HCN

Question 9

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

A) CH₃Cl
B) F₂
C) Ne
D) CO₂
E) Kr

Question 10

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

A) SF₆
B) CO₂
C) O₂
D) N₂
E) CH₄

Question 11

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

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

Question 12

"Isothermal" means .

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

Question 13

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

A) NH₃
B) HCN
C) CO
D) CH₄
E) N₂O

Question 14

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

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

Question 15

A fixed amount of gas at 25.0 °C occupies a volume of 10.0 L when the pressure is 629 torr. Use Charles's law to calculate the volume (L) the gas will occupy when the temperature is increased to 121 °C while maintaining the pressure at 629 torr.

A) 13.2
B) 7.56
C) 10.9
D) 2.07
E) 48.4

Question 16

Zinc reacts with aqueous sulfuric acid to form hydrogen gas:

In an experiment, 201 mL of wet H₂ is collected over water at 27 °C and a barometric pressure of 733 torr. The vapor pressure of water at 27 °C is 26.74 torr. The partial pressure of hydrogen in this experiment is _ atm.

A) 0.964
B) 706
C) 760
D) 0.929
E) 1.00

Question 17

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^{- 1}K^{- 1}
B) 1.987 cal mol^{- 1}K^{- 1}
C) 8.314 J mol^{- 1}K^{- 1}
D) 62.36 L torr mol^{- 1}K^{- 1}
E) none of the above

Question 18

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 an average molecular mass
C) have a molecular weight of zero
D) have no kinetic energy
E) have appreciable molecular volumes

Question 19

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

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

Question 20

A 1.44- g sample of an unknown pure gas occupies a volume of 0.335 L at a pressure of 1.00 atm and a temperature of 100.0 °C. The unknown gas is _.

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

Question 21

Of the following gases, has density of 2.104 g/L at 303 K and 1.31 atm.

A) Ar
B) Ne
C) Xe
D) He
E) Kr

Question 22

Removal of _ from the natural gas both purifies the natural gas and serves as an alternative method of production of an industrially important chemical element.

A) CO₂
B) As₂O₃
C) H₂S
D) He
E) NH₃

Question 23

How much faster does ²³⁵UF₆ effuse than ²³⁸UF₆?

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

Question 24

Which statement about ideal behavior of gases is false?

A) Volume of 2.00 moles of oxygen gas, O₂, is assumed to be the same as that of 2.00 moles of carbon dioxide gas, CO₂, as long as the temperature and pressure conditions are the same.
B) Low pressures and high temperatures typically cause deviations from the ideal gas behavior.
C) At low densities all gases have similar properties.
D) All particles in the ideal gas behave independently of each other.
E) Gas ideality assumes that there are no interactions between gas particles.

Question 25

A fixed amount of gas at 25.0 °C occupies a volume of 10.0 L when the pressure is 667 torr. Use Boyle's law to calculate the pressure (torr) when the volume is reduced to 7.88 L at a constant temperature of 25.0 °C.

A) 526
B) 5.26 × 10⁴
C) 1.11
D) 846
E) 0.118

Question 26

The molar volume of a gas at STP is L.

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

Question 27

Arrange the following gases in order of increasing average molecular speed at 25 °C.

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

Question 28

The density of chlorine gas at 1.21 atm and 34.9 °C is g/L.

A) 1.70
B) 3.39
C) 0.0479
D) 0.295
E) 0.423

Question 29

Calcium hydride (CaH₂) reacts with water to form hydrogen gas:

How many grams of CaH₂ are needed to generate 48.0 L of H₂ gas at a pressure of 0.888 atm and a temperature of 32 °C?

A) 50.7
B) 71.7
C) 143
D) 35.8
E) 0.851

Question 30

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) 16.3
C) 0.247
D) 0.497
E) 2.01

Question 31

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

A) HBr
B) NH₃
C) CH₄
D) HCl
E) Ar

Question 32

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

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

Question 33

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

A) Ne
B) NH₃
C) NO₂
D) SO₂
E) SO₃

Question 34

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) NH₃
B) NO
C) Ne
D) HF
E) CH₄

Question 35

The total pressure exerted by a mixture of 1.50 g of H₂ and 5.00 g of N₂ in a 5.00- L vessel at 298 K is atm.

A) 4.54
B) 32.4
C) 1.06
D) 5.27
E) 9.08

Question 36

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 CO₂
C) NO₂ and N₂O₄
D) N₂ and O₂
E) CO and N₂

Question 37

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

Question 38

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

Question 39

Of the following, is a greenhouse gas.

A) Xe
B) CH₄
C) Cl₂
D) O₂
E) C₂H₄

Question 40

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 115.23g Which of the following compounds could the liquid be? (Assume the ambient pressure is 1 atm.)

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

Question 41

Molecular compounds of low molecular weight tend to be gases at room temperature. Which of the following is most likely not a gas at room temperature?

A) LiCl
B) HCl
C) CH₄
D) Cl₂
E) H₂

Question 42

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

Question 43

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

Question 44

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

Question 45

The volume of an ideal gas is zero at .

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

Question 46

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) H₂
B) HCl
C) SO₂
D) Cl₂
E) CO

Question 47

One significant difference between gases and liquids is that _ .

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

Question 48

Gaseous mixtures .

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

Question 49

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

A) the gas molecules collide less frequently with the wall
B) the gas molecules collide more frequently with the wall
C) the average kinetic energy of the gas molecules decreases
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 50

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

A) 298 K and 1 atm
B) 273 K and 1 atm
C) 273 K and 1 torr
D) 298 K and 1 torr
E) 273 K and 1 pascal

Question 51

Arrange the following gases in order of increasing average molecular speed at 25 °C.

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

Question 52

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

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

Question 53

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

Question 54

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

A)
B)
C)
D)
E)

Question 55

The density of is 0.900 g/L at STP.

A) CH₄
B) NO
C) N₂
D) CO
E) Ne

Question 56

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

Question 57

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

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

Question 58

Which statement about atmospheric pressure is false?

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

Question 59

The density of nitric oxide (NO) gas at 1.21 atm and 54.1 °C is g/L.

A) 1.35
B) 0.0451
C) 0.273
D) 8.2
E) 0.740

Question 60

Zinc reacts with aqueous sulfuric acid to form hydrogen gas:

In an experiment, 225 mL of wet H₂ is collected over water at 27 °C and a barometric pressure of 748 torr. How many grams of Zn have been consumed? The vapor pressure of water at 27 °C is
26)74 torr.

A) 567
B) 4.79 × 10⁶
C) 4.31 × 10⁵
D) 0.567
E) 431

Question 61

The volume of 0.65 mol of an ideal gas at 365 torr and 97 °C is _ L.

A) 0.054
B) 9.5
C) 41
D) 11
E) 2.4 × 10^{- 2}

Question 62

A sample of He gas (3.0 L) at 5.6 atm and 25 °C was combined with 4.5 L of Ne gas at 3.6 atm and 25 °C at constant temperature in a 9.0 L flask. The total pressure in the flask was atm. Assume the initial pressure in the flask was 0.00 atm.

A) 24
B) 1.0
C) 3.7
D) 2.6
E) 9.2

Question 63

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 [ ^P2 ] is .
P₁

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

Question 64

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) 578
D) 1.73 × 10^{- 3}
E) 141

Question 65

The rms speed of methane molecules at 45.0 °C is m/sec.

Question 66

What is the density (in g/L) of oxygen gas at 77 ^oC and 700 torr?

Question 67

What is the partial pressure (in mm Hg) of neon in a 4.00 L vessel that contains 0.838 mol of methane, 0.184 mol of ethane, and 0.755 mol of neon at a total pressure of 928 mmHg?

Question 68

Given the equation
Determine the number of liters of O₂ consumed at STP when 270.0 grams of C₂H₆ is burned.

Question 69

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

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

Question 70

How many molecules are there in 4.00 L of oxygen gas at 500 ^oC and 50.0 torr?

Question 71

A closed- end manometer was attached to a vessel containing argon. The difference in the mercury levels in the two arms of the manometer was 12.2 cm. Atmospheric pressure was 783 mmHg. The pressure of the argon in the container was mmHg.

A) 661
B) 122
C) 882
D) 771
E) 795

Question 72

The temperature and pressure specified by STP are ^oC and atm.

Question 73

A sample of O₂ gas (2.0 mmol) effused through a pinhole in 5.0 s. It will take s for the same amount of CO₂ to effuse under the same conditions.

A) 6.9
B) 3.6
C) 4.3
D) 5.9
E) 0.23

Question 74

The amount of gas that occupies 60.82 L at 31 °C and 367 mmHg is mol.

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

Question 75

The density of chlorine (Cl₂) gas at 25 °C and 60. kPa is g/L)

A) 20
B) 4.9
C) 0.86
D) 0.58
E) 1.7

Question 76

A vessel contained N₂, Ar, He, and Ne. The total pressure in the vessel was 987 torr. The partial pressures of nitrogen, argon, and helium were 44.0, 486, and 218 torr, respectively. The partial pressure of neon in the vessel was torr.

A) 239
B) 521
C) 19.4
D) 42.4
E) 760

Question 77

Given the equation
Determine the number of liters of CO₂ formed at STP. when 240.0 grams of C₂H₆ is burned in excess oxygen gas.

Question 78

Using the van der Waals equation, the pressure in a 22.4 L vessel containing 1.00 mol of neon gas at 100 °C is atm. (a = 0.211 L²- atm/mol², b = 0.0171 L/mol)

A) 1.00
B) 0.730
C) 1.21
D) 1.37
E) 0.367

Question 79

The reaction of 50 mL of Cl₂ gas with 50 mL of CH₄ 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) 125
B) 150
C) 50
D) 25
E) 100

Question 80

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 molecular attractions between particles of gas decreases the pressure exerted by the gas
D) the non- zero volumes of gas particles effectively decrease the amount of "empty space" between them
E) all of the above statements are true