Deck 5: Gases

Question 1

If the volume of a confined gas is expanded to four times the original volume while its temperature remains constant,what change will be observed?

A) The pressure of the gas will decrease to 1/4 of its original value.
B) The pressure of the gas will decrease to 1/2 of its original value.
C) The pressure of the gas will remain unchanged.
D) The pressure of the gas will increase to twice its original value.
E) The pressure of the gas will increase to four times its original value.

Answer 1

The pressure of the gas will decrease to 1/4 of its original value.

Question 2

If 8.5 g of oxygen gas (O₂)is introduced into an evacuated 1.50 L flask at 22°C,what is the pressure inside the flask?

A) 0.32 atm
B) 0.48 atm
C) 4.3 atm
D) 6.4 atm
E) 137 atm

Answer 2

4.3 atm

Question 3

A 3.00 L flask contains 2.33 g of argon gas at 312 mm Hg.What is the temperature of the gas?

A) 151 K
B) 257 K
C) 292 K
D) 341 K
E) 4890 K

Answer 3

257 K

Question 4

Avogadro's law states that

A) 1 liter of any gas contains 6.02 × 10²³ gas molecules.
B) the volume of a gas is directly proportional to its temperature.
C) the gas constant equals 0.0821 L · atm/(mol · K)for all ideal gases.
D) the volume of a gas must always be a constant.
E) equal volumes of all gases at the same pressure and temperature contain an equal number of moles.

Question 5

A bicycle tire is filled to a pressure of 4.42 atm (65 psi)at a temperature of 12°C.If the temperature of the tire increases to 33°C,what is the pressure in the tire? Assume the volume of the tire is constant.

A) 4.75 atm
B) 5.91 atm
C) 9.28 atm
D) 12.1 atm
E) 16.1 atm

Question 6

A balloon is filled with He gas to a volume of 2.10 L at 35°C.The balloon is placed in liquid nitrogen until its temperature reaches -196°C.Assuming the pressure remains constant,what is the volume of the cooled balloon?

A) −0.375 L
B) 0.375 L
C) 0.525 L
D) 0.00909 L
E) 8.40 L

Question 7

At 28°C,a gas cylinder containing hydrogen has an internal volume and pressure of 46.6 L and 1.50 × 10² atm.The gas is allowed to escape the cylinder and expand until its pressure reaches 1.00 atmosphere.If the temperature of the gas remains constant,what volume will the gas occupy?

A) 0.311 L
B) 2.22 L
C) 46.6 L
D) 6.99 × 10³ L
E) 8.91 × 10³ L

Question 8

At 21°C,a gas cylinder containing nitrogen has an internal volume and pressure of 46.6 L and 1.50 × 10² atm.What mass of nitrogen gas is contained in the cylinder?

A) 2.90 × 10² g
B) 4.05 × 10³ g
C) 8.11 × 10³ g
D) 1.14 × 10⁵ g
E) none of the above

Question 9

A balloon with a volume of 8.73 L contains 0.321 moles of helium gas.What is the density of the gas?

A) 0.0368 g/L
B) 0.147 g/L
C) 0.700 g/L
D) 2.80 g/L
E) 27.1 g/L

Question 10

At 338 mm Hg and 72°C,a sample of carbon monoxide gas occupies a volume of 0.225 L.The gas is transferred to a 1.50-L flask and the temperature is reduced to -15°C.What is the pressure of the gas in the flask?

A) 8.91 mm Hg
B) 37.9 mm Hg
C) 67.8 mm Hg
D) 3.018 × 10³ mm Hg
E) 5.48 × 10⁴ mm Hg

Question 11

What volume of Ar at 45°C and 1.25 atm contains the same number of particles as 0.655 L of H₂ at 15°C and 2.00 atm?

A) 0.452 L
B) 1.16 L
C) 0.949 L
D) 0.371 L
E) 3.14 L

Question 12

The molar masses of helium and oxygen are 4.0 g/mol and 16 g/mol,respectively.At the same temperature and pressure,1 mole of helium will occupy

A) the same volume as 1 mole of oxygen.
B) four times the volume of 1 mole of oxygen.
C) twice the volume of 1 mole of oxygen.
D) half the volume of 1 mole of oxygen.
E) one-fourth the volume of 1 mole of oxygen.

Question 13

All of the following relationships are false for gases EXCEPT

A) volume is inversely proportional to the number of moles for a gas.
B) volume is directly proportional to pressure in mm Hg.
C) volume is directly proportional to pressure in atmospheres.
D) volume is directly proportional to temperature in Kelvin.
E) volume is directly proportional to the gas constant R.

Question 14

A mass of 5.0 grams of dry ice,CO₂(s),is sealed in an evacuated 2.0 L plastic soda bottle.What is the pressure inside the bottle when the CO₂ is heated to 35°C?

A) 0.16 atm
B) 1.4 atm
C) 8.9 atm
D) 18 atm
E) 63 atm

Question 15

Place the following units of pressure in order from lowest to highest pressure.

A) 1 atm < 1 Pa < 1 mm Hg < 1 bar
B) 1 mm Hg < 1 bar < 1 atm < 1 Pa
C) 1 Pa < 1 mm Hg < 1 bar < 1 atm
D) 1 Pa < 1 mm Hg < 1 atm < 1 bar
E) 1 bar < 1 mm Hg < 1 Pa < 1 atm

Question 16

A balloon is filled with 1.50 L of helium gas at sea level,1.00 atm and 32°C.The balloon is released and it rises to an altitude of 30,000 ft.If the pressure at this altitude is 228 mm Hg and the temperature is −45°C,what is the volume of the balloon?

A) 0.336 L
B) 1.56 L
C) 1.68 L
D) 2.81 L
E) 3.74 L

Question 17

A mass of 1.37 g of an unknown gas is introduced into an evacuated 1.70 L flask.If the pressure in the flask is 0.814 atm at 98°C,which of the following gases might be in the flask? (R = 0.0821 L · atm/mol · K)

A) CH₄
B) C₂H₂
C) C₂H₆
D) C₃H₈
E) C₄H₁₀

Question 18

A tightly sealed 4.0-L flask contains 884 mm Hg of N₂ at 94.0°C.The flask is cooled until the pressure is reduced to 442 mm Hg.What is the temperature of the gas?

A) -47.0°C
B) 47.0°C
C) -89.5°C
D) 184°C
E) 188°C

Question 19

At 108°C,the pressure in a 10.0 L flask is 874 mm Hg.How many moles of gas are in the flask?

A) 0.368 mol
B) 0.873 mol
C) 1.30 mol
D) 348 mol
E) 986 mol

Question 20

What volume does 22.4 moles of hydrogen gas occupy at 0°C and 1.00 atm?

A) 0.0821 L
B) 1.00 L
C) 22.4 L
D) 184 L
E) 502 L

Question 21

The composition (in mole percent)of the atmosphere is 78.1% N₂,21.0% O₂,and 0.9% Ar.What is the partial pressure of each gas when the barometric pressure is 754.1 mm Hg?

A) N₂ = 21.1 atm,O₂ = 6.5 atm,Ar = 0.3 atm
B) N₂ = 78.1 mm Hg,O₂ = 21.0 mm Hg,Ar = 0.9 mm Hg
C) N₂ = 244 mm Hg,O₂ = 244 mm Hg,Ar = 244 mm Hg
D) N₂ = 405 mm Hg,O₂ = 234 mm Hg,Ar = 293 mm Hg
E) N₂ = 589 mm Hg,O₂ = 158 mm Hg,Ar = 7 mm Hg

Question 22

Which of the following gases has the greatest density at 35 °C and 450 mm Hg?

A) CH₄
B) Ar
C) N₂
D) Cl₂
E) C₃H₈

Question 23

The density of hydrogen gas in a flask is 0.147 g/L at 305 K.What is the pressure inside the flask?

A) 0.139 atm
B) 1.19 atm
C) 1.84 atm
D) 2.98 atm
E) 3.69 atm

Question 24

A volume of 3.0 L of butane is burned in excess oxygen.Balance the chemical equation below and determine how many total liters of gases are produced.Assume that both the reactant and product temperature is 500 K and the pressure of the system remains constant at 1.0 atm. C₄H₁₀(g)+ O₂(g)→ CO₂(g)+ H₂O(g)

A) 3.0 L
B) 6.0 L
C) 12 L
D) 27 L
E) 42 L

Question 25

At 1.00 km above sea level,the atmospheric pressure is 675 mm Hg and the temperature is 282 K.If nitrogen comprises 78.1% (mole percent)of air,what is the density of nitrogen at this height?

A) 0.0238 g/L
B) 0.521 g/L
C) 0.839 g/L
D) 1.07 g/L
E) 638 g/L

Question 26

Ammonia gas is produced commercially from the reaction of nitrogen and hydrogen.What volume of ammonia can be produced from the reaction of 5.5 × 10³ kg of N₂ and 1.5 × 10³ kg of H₂? Assume the reaction is 100% efficient and the product is collected at 325 K and 25 atm. N₂(g)+ 3H₂(g)→ 2NH₃(g)

A) 7.0 × 10³ L
B) 1.4 × 10⁴ L
C) 1.8 × 10⁴ L
D) 4.2 × 10⁵ L
E) 5.2 × 10⁵ L

Question 27

Aqueous hydrochloric acid reacts with magnesium to produce hydrogen gas according to the balanced equation below. 2H⁺(aq)+ Mg(s)→ Mg²⁺(aq)+ H₂(g)
If 250.0 mL of 3.00 M HCl is combined with 9.92 g Mg,what volume of hydrogen gas can be produced? Assume the temperature and pressure of the gas are 25°C and 0.988 atm,respectively.(R = 0.0821 L⋅atm/mol⋅K)

A) 4.60 L
B) 5.05 L
C) 9.29 L
D) 10.1 L
E) 18.6 L

Question 28

A volatile compound with a mass of 0.8822 grams is placed in an evacuated 0.250 L flask.The flask is heated to evaporate the compound.At 99°C,the pressure in the flask is 1.25 atm.What is the molar mass of the compound?

A) 86.2 g/mol
B) 116 g/mol
C) 229 g/mol
D) 257 g/mol
E) 303 g/mol

Question 29

Nitroglycerin (227.1 g/mol)releases a large amount of energy and gaseous products upon decomposition.If 10.00 grams of nitroglycerin decomposes in an evacuated 1.00 L flask,what is the pressure inside the flask? Assume the temperature is 4.00 × 10² K and that the flask survives the explosion. 4C₃H₅N₃O₉(l)→ 6N₂(g)+ 12CO₂(g)+ 10H₂O(g)+ O₂(g)

A) 1.45 atm
B) 10.5 atm
C) 41.9 atm
D) 328 atm
E) 952 atm

Question 30

An unknown gas contains 85.6% C and 14.4% H.At 0.455 atm and 425 K,the gas has a density of 0.549 g/L.What is the molecular formula of the gas?

A) CH₄
B) C₂H₄
C) C₃H₆
D) C₄H₆
E) C₄H₈

Question 31

A 10.0 L flask contains 2.5 atm of ethane gas and 8.0 atm of oxygen gas at 28°C.The contents of the flask react until the limiting reactant is consumed.What is the pressure of carbon dioxide in the flask after the temperature returns to 28°C? 2C₂H₆(g)+ 7O₂(g)→ 4CO₂(g)+ 6H₂O(g)

A) 2.5 atm
B) 4.6 atm
C) 5.0 atm
D) 5.5 atm
E) 10.5 atm

Question 32

A mixture of H₂ and O₂ is placed in a 5.00 L flask at 22 °C.The partial pressure of the H₂ is 2.7 atm and the partial pressure of the O₂ is 1.5 atm.What is the mole fraction of H₂?

A) 0.13
B) 0.36
C) 0.56
D) 0.64
E) 0.87

Question 33

Sulfur burns in oxygen with a deep blue flame to produce sulfur dioxide.If 5.85 g S₈ and 1.00 atm of O₂ completely react in a 5.00 L flask (at 25°C),determine the partial pressure of SO₂ (at 25°C)and the total pressure in the flask. S₈(s)+ 8O₂(g)→ 8SO₂(g)

A) O₂ = 0 atm,SO₂ = 1.00 atm,total pressure = 1.00 atm
B) O₂ = 0.093 atm,SO₂ = 0.917 atm,total pressure = 1.00 atm
C) O₂ = 0.107 atm,SO₂ = 0.893 atm,total pressure = 1.00 atm
D) O₂ = 0.855 atm,SO₂ = 0.145 atm,total pressure = 1.00 atm
E) O₂ = 0.917 atm,SO₂ = 0.163 atm,total pressure = 1.08 atm

Question 34

At what temperature does 1.00 atm of carbon dioxide (CO₂)gas have the same density as 1.00 atm of helium gas at 25°C?

A) 0 K
B) 25 K
C) 482 K
D) 983 K
E) 3.28 × 10³ K

Question 35

If 5.00 L of propane is burned in 21.0 L of oxygen,what volume of carbon dioxide is produced? Assume that the temperature of the reactants and products is 25°C and the pressure of the system remains constant at 1.0 atm. C₃H₈(g)+ 5O₂(g)→ 3CO₂(g)+ 4H₂O(l)

A) 12.6 L
B) 15.0 L
C) 21.0 L
D) 25.6 L
E) 26.0 L

Question 36

Calculate the density (in g/L)of CH₄(g)at 75°C and 2.1 atm.(R = 0.08206 L · atm/mol · K)

A) 0.18 g/L
B) 0.85 g/L
C) 1.2 g/L
D) 3.2 g/L
E) 5.5 g/L

Question 37

An unknown mass of ammonium perchlorate,NH₄ClO₄ (117.5 g/mol),is placed in an evacuated 1.00 L flask and heated to 251°C.At this temperature the NH₄ClO₄ decomposes violently.The gaseous products exert a pressure of 466 mm Hg at 251°C.What mass of NH₄ClO₄ was placed in the flask? 2NH₄ClO₄(s)→ N₂(g)+ Cl₂(g)+ 2O₂(g)+ 4H₂O(g)

A) 0.149 g
B) 0.419 g
C) 0.682 g
D) 1.67 g
E) 3.19 g

Question 38

If 6.46 L of gaseous ethanol reacts with 16.1 L O₂,what is the maximum volume of gaseous carbon dioxide produced? Assume that the temperature of the reactants and products is 425°C and the pressure remains constant at 1.00 atm. CH₃CH₂OH(g)+ 3O₂(g)→ 2CO₂(g)+ 3H₂O(g)

A) 6.46 L
B) 10.7 L
C) 12.9 L
D) 16.1 L
E) 22.6 L

Question 39

Water can be decomposed by electrolysis to hydrogen gas and oxygen gas.What mass of water must decompose to yield 24.0 L of oxygen gas at 1.00 atm and 25°C? 2H₂O(l)→ 2H₂(g)+ O₂(g)

A) 11.1 g
B) 17.7 g
C) 23.6 g
D) 35.3 g
E) 70.7 g

Question 40

What volume of O₂,measured at 225°C and 0.970 atm,will be produced by the decomposition of 3.16 g KClO₃? (R = 0.08206 L · atm/mol · K) 2KClO₃(s)→ 2KCl(s)+ 3O₂(g)

A) 1.09 L
B) 1.24 L
C) 1.63 L
D) 3.26 L
E) 52.1 L

Question 41

In an experiment,argon is allowed to effuse through a tiny opening into an evacuated 5.00 × 10² mL flask for 30.0 seconds,at which point the pressure in the flask is found to be 15.0 mm Hg.The experiment is repeated using an unknown gas at the same temperature and pressure.After 30.0 seconds,the pressure is found to be 47.4 mm Hg.What is the molar mass of the gas?

A) 4.00 g/mol
B) 16.0 g/mol
C) 28.0 g/mol
D) 32.0 g/mol
E) 83.8 g/mol

Question 42

At 25°C,the average speed of a hydrogen molecule is 1.92 × 10³ m/s.What is the average speed of a nitrogen molecule at the same temperature?

A) 138 m/s
B) 515 m/s
C) 7.16 × 10³ m/s
D) 2.67 × 10⁴ m/s
E) none of the above

Question 43

SF₆(g)can be used as an insulating gas between glass panes of a window.If the temperature of the gas is 10°C,what is the average speed of the gas?

A) 41.3 m/s
B) 372 m/s
C) 706 m/s
D) 484 m/s
E) 220 m/s

Question 44

Water can be decomposed by electrolysis to hydrogen gas and oxygen gas.If 2.33 g of water is decomposed to H₂(g)and O₂(g)and the gases are collected in a 1.00 L flask over water at 25°C (vapor pressure H₂O(l)= 23.8 mm Hg),what is the pressure in the flask?

A) 3.19 atm
B) 4.71 atm
C) 4.75 atm
D) 4.78 atm
E) 9.52 atm

Question 45

A 10.0 L flask is used to collect 0.500 moles of N₂ and 0.180 moles of O₂ over water at 30°C.What is the pressure in the flask? (vapor pressure H₂O(l)= 31.8 mm Hg)

A) −30.1 atm
B) 1.15 atm
C) 1.48 atm
D) 1.69 atm
E) 1.73 atm

Question 46

The average speed of a gas molecule is

A) inversely proportional to the square root of its mass.
B) inversely proportional to the gas constant,R.
C) directly proportional to the square of its temperature in K.
D) inversely proportional to its kinetic energy.
E) directly proportional to the square of its temperature in °C.

Question 47

A sample of carbon dioxide is collected over water at 25°C (vapor pressure H₂O(l)= 23.8 mm Hg).The CO₂ and water vapor occupy a volume of 1.80 L at a pressure of 783.0 mm Hg.What mass of CO₂ is present?

A) 3.23 g
B) 4.40 g
C) 9.02 g
D) 14.7 g
E) 16.3 g

Question 48

At a given temperature,molecules of different gases

A) have the same average kinetic energy of translational motion.
B) have the same average velocity.
C) have the same diameter.
D) have the same density.
E) have identical masses.

Question 49

One way in which real gases differ from ideal gases is that the molecules of a real gas

A) have no kinetic energy.
B) move in curved paths.
C) have no mass.
D) occupy no volume.
E) are attracted to each other.

Question 50

At what temperature does O₂ have the same average speed as H₂ does at 273 K?

A) 273 K
B) 389 K
C) 498 K
D) 658 K
E) 4.33 × 10³ K

Question 51

Methane gas,CH₄,effuses through a barrier at a rate of 0.568 mL/minute.If an unknown gas effuses through the same barrier at a rate of 0.343 mL/minute,what is the molar mass of the gas?

A) 20.8 g/mol
B) 28.0 g/mol
C) 32.0 g/mol
D) 43.9 g/mol
E) 64.0 g/mol

Question 52

Which conditions will cause the greatest deviation from the ideal gas law?

A) 100 atm and 500 K
B) 100 atm and 10 K
C) 0.001 atm and 500 K
D) 0.001 atm and 10 K
E) 0.001 atm and 273 K