Question 1

Nitrogen dioxide is a red-brown gas that is responsible for the color of photochemical smog. A sample of nitrogen dioxide has a volume of 28.6 L at 45.3°C and 89.9 kPa. What is its volume at STP?

Accepted Answer

A)  21.8 L
B)  27.6 L
C)  29.6 L
D)  37.6 L
E)  153 LF) None of the above
G) A) and B)

Question 2

A 3.0-L sample of helium was placed in a container fitted with a porous membrane. Half of the helium effused through the membrane in 24 hours. A 3.0-L sample of oxygen was placed in an identical container. How many hours will it take for half of the oxygen to effuse through the membrane?

Accepted Answer

A)  8.5 h
B)  12 h
C)  48 h
D)  60. h
E)  68 hF) A) and B)
G) A) and C)

Question 3

The volume of a single molecule of water is 2.99 × 10−23 mL. For a sample of gaseous water at 1.00 atm and 150°C, what fraction of the container's volume is occupied by the molecules themselves?

Accepted Answer

A)  5.2 × 10 −7
B)  4.5 × 10 −5
C)  5.2 × 10 −4
D)  5.2 × 10 −1
E)  None of these choices are correct.F) A) and D)
G) All of the above

Question 4

Which of the lines on the figure below is the best representation of the relationship between the volume and the number of moles of a gas, measured at constant temperature and pressure?

Accepted Answer

A)  a
B)  b
C)  c
D)  d
E)  eF) All of the above
G) C) and D)

Question 5

A flask with a volume of 3.16 L contains 9.33 grams of an unknown gas at 32.0°C and 1.00 atm. What is the molar mass of the gas?

Accepted Answer

A)  7.76 g/mol
B)  66.1 g/mol
C)  74.0 g/mol
D)  81.4 g/mol
E)  144 g/molF) C) and D)
G) A) and B)

Question 6

A 250.0-mL sample of ammonia, NH3(g) , exerts a pressure of 833 torr at 42.4°C. What mass of ammonia is in the container?

Accepted Answer

A)  0.0787 g
B)  0.180 g
C)  8.04 g
D)  17.0 g
E)  59.8 gF) A) and D)
G) B) and C)

Question 7

"The pressure of an ideal gas is inversely proportional to its volume at constant temperature and number of moles" is a statement of __________ Law.

Accepted Answer

A)  Charles's
B)  Boyle's
C)  Amontons's
D)  Avogadro's
E)  Gay-Lussac'sF) C) and D)
G) A) and B)

Question 8

Assuming ideal behavior, what is the density of argon gas at STP, in g/L?

Accepted Answer

A)  0.0176 g/L
B)  0.0250 g/L
C)  0.0561 g/L
D)  1.78 g/L
E)  181. g/LF) A) and B)
G) A) and D)

Question 9

A flask containing argon gas is connected to a closed-ended mercury manometer. The closed end is under vacuum. If the mercury level in the closed arm is 230. mm above that in the arm connected to the flask, what is the argon pressure, in torr?

Accepted Answer

A)  −230.
B)  230.
C)  530.
D)  790.
E)  None of these choices are correct.F) A) and B)
G) All of the above

Question 10

Which of the following gases will be the slowest to diffuse through a room?

Accepted Answer

A)  Methane, CH 4
B)  Hydrogen sulfide, H 2S
C)  Carbon dioxide, CO 2
D)  Water, H 2O
E)  Neon, NeF) A) and B)
G) B) and D)

Question 11

According to the postulates of kinetic-molecular theory, the molecules of all gases at a given temperature have the same average speed.

Accepted Answer

A) True 
 B)False

Question 12

If the molecular mass of a gas increases by a factor of 4 at constant temperature, its rms speed will

Accepted Answer

A)  decrease by a factor of 4.
B)  increase by a factor of 4.
C)  decrease by a factor of 16.
D)  increase by a factor of 16.
E)  decrease by a factor of 2.F) B) and D)
G) B) and C)

Question 13

Dr. I. M. A. Brightguy adds 0.1727 g of an unknown gas to a 125-mL flask. If Dr. B finds the pressure to be 736 torr at 20.0°C, is the gas likely to be methane, CH4, nitrogen, N2, oxygen, O2, neon, Ne, or argon, Ar?

Accepted Answer

A)  CH 4
B)  N 2
C)  Ne
D)  Ar
E)  O 2F) B) and E)
G) B) and D)

Question 14

A 750-mL sample of hydrogen exerts a pressure of 822 torr at 325 K. What pressure does it exert if the temperature is raised to 475 K at constant volume?

Accepted Answer

A)  188 torr
B)  562 torr
C)  1.11 × 10 3 torr
D)  1.20 × 10 3 torr
E)  1.90 × 10 3 torrF) A) and C)
G) A) and E)

Question 15

A sample of methane gas, CH4(g) , occupies a volume of 60.3 L at a pressure of 469 torr and a temperature of 29.3°C. What would be its temperature at a pressure of 243 torr and volume of 60.3 L?

Accepted Answer

A)  −116.5°C
B)  15.2°C
C)  15.5°C
D)  57.7°C
E)  310.6°CF) A) and B)
G) D) and E)

Question 16

A flask containing neon gas is connected to an open-ended mercury manometer. The open end is exposed to the atmosphere, where the prevailing pressure is 745 torr. The mercury level in the open arm is 50. mm below that in the arm connected to the flask of neon. What is the neon pressure, in torr?

Accepted Answer

A)  −50. torr
B)  50. torr
C)  695 torr
D)  795 torr
E)  None of these choices are correct.F) None of the above
G) A) and E)

Question 17

Magnesium metal (0.100 mol)  and a volume of aqueous hydrochloric acid that contains 0.500 mol of HCl are combined and react to completion. How many liters of hydrogen gas, measured at STP, are produced? Mg(s)  + 2HCl(aq)  → MgCl2(aq)  + H2(g)

Accepted Answer

A)  2.24 L of H 2
B)  4.48 L of H 2
C)  5.60 L of H 2
D)  11.2 L of H 2
E)  22.4 L of H 2F) A) and B)
G) C) and E)

Question 18

Hydrogen gas exerts a pressure of 466 torr in a container. What is this pressure in atmospheres?

Accepted Answer

A)  0.217 atm
B)  0.466 atm
C)  0.613 atm
D)  1.63 atm
E)  4.60 atmF) A) and E)
G) B) and D)

Question 19

A sample of an ideal gas has its volume doubled while its temperature remains constant. If the original pressure was 100 torr, what is the new pressure?

Accepted Answer

A)  10 torr
B)  50 torr
C)  100 torr
D)  200 torr
E)  1000 torrF) A) and E)
G) A) and D)

Question 20

Hydrogen peroxide was catalytically decomposed and 75.3 mL of oxygen gas was collected over water at 25°C and 742 torr. What mass of oxygen was collected? (Pwater = 24 torr at 25°C)

Accepted Answer

A)  0.00291 g
B)  0.0931 g
C)  0.0962 g
D)  0.0993 g
E)  0.962 gF) A) and D)
G) A) and E)

Exam 5: Gases and the Kinetic-Molecular Theory

A sample of methane gas, CH4(g) , occupies a volume of 60.3 L at a pressure of 469 torr and a temperature of 29.3°C. What would be its temperature at a pressure of 243 torr and volume of 60.3 L?

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Hydrogen peroxide was catalytically decomposed and 75.3 mL of oxygen gas was collected over water at 25°C and 742 torr. What mass of oxygen was collected? (Pwater = 24 torr at 25°C)

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A flask containing neon gas is connected to an open-ended mercury manometer. The open end is exposed to the atmosphere, where the prevailing pressure is 745 torr. The mercury level in the open arm is 50. mm below that in the arm connected to the flask of neon. What is the neon pressure, in torr?

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Which of the following gases will be the slowest to diffuse through a room?

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Assuming ideal behavior, what is the density of argon gas at STP, in g/L?

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Nitrogen dioxide is a red-brown gas that is responsible for the color of photochemical smog. A sample of nitrogen dioxide has a volume of 28.6 L at 45.3°C and 89.9 kPa. What is its volume at STP?

Correct AnswerverifiedShow Answer

Which of the lines on the figure below is the best representation of the relationship between the volume and the number of moles of a gas, measured at constant temperature and pressure?

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A flask containing argon gas is connected to a closed-ended mercury manometer. The closed end is under vacuum. If the mercury level in the closed arm is 230. mm above that in the arm connected to the flask, what is the argon pressure, in torr?

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According to the postulates of kinetic-molecular theory, the molecules of all gases at a given temperature have the same average speed.

Correct AnswerverifiedShow Answer

Magnesium metal (0.100 mol) and a volume of aqueous hydrochloric acid that contains 0.500 mol of HCl are combined and react to completion. How many liters of hydrogen gas, measured at STP, are produced? Mg(s) + 2HCl(aq) → MgCl2(aq) + H2(g)

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Dr. I. M. A. Brightguy adds 0.1727 g of an unknown gas to a 125-mL flask. If Dr. B finds the pressure to be 736 torr at 20.0°C, is the gas likely to be methane, CH4, nitrogen, N2, oxygen, O2, neon, Ne, or argon, Ar?

Correct AnswerverifiedShow Answer

If the molecular mass of a gas increases by a factor of 4 at constant temperature, its rms speed will

Correct AnswerverifiedShow Answer

A flask with a volume of 3.16 L contains 9.33 grams of an unknown gas at 32.0°C and 1.00 atm. What is the molar mass of the gas?

Correct AnswerverifiedShow Answer

The volume of a single molecule of water is 2.99 × 10−23 mL. For a sample of gaseous water at 1.00 atm and 150°C, what fraction of the container's volume is occupied by the molecules themselves?

Correct AnswerverifiedShow Answer

Hydrogen gas exerts a pressure of 466 torr in a container. What is this pressure in atmospheres?

Correct AnswerverifiedShow Answer

A 750-mL sample of hydrogen exerts a pressure of 822 torr at 325 K. What pressure does it exert if the temperature is raised to 475 K at constant volume?

Correct AnswerverifiedShow Answer

A sample of an ideal gas has its volume doubled while its temperature remains constant. If the original pressure was 100 torr, what is the new pressure?

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A 3.0-L sample of helium was placed in a container fitted with a porous membrane. Half of the helium effused through the membrane in 24 hours. A 3.0-L sample of oxygen was placed in an identical container. How many hours will it take for half of the oxygen to effuse through the membrane?

Correct AnswerverifiedShow Answer

"The pressure of an ideal gas is inversely proportional to its volume at constant temperature and number of moles" is a statement of __________ Law.

Correct AnswerverifiedShow Answer

A 250.0-mL sample of ammonia, NH3(g) , exerts a pressure of 833 torr at 42.4°C. What mass of ammonia is in the container?

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A sample of methane gas, CH₄(g) , occupies a volume of 60.3 L at a pressure of 469 torr and a temperature of 29.3°C. What would be its temperature at a pressure of 243 torr and volume of 60.3 L?

Correct Answer
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Hydrogen peroxide was catalytically decomposed and 75.3 mL of oxygen gas was collected over water at 25°C and 742 torr. What mass of oxygen was collected? (P_water = 24 torr at 25°C)

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Magnesium metal (0.100 mol) and a volume of aqueous hydrochloric acid that contains 0.500 mol of HCl are combined and react to completion. How many liters of hydrogen gas, measured at STP, are produced? Mg(s) + 2HCl(aq) → MgCl₂(aq) + H₂(g)

Correct Answer
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Dr. I. M. A. Brightguy adds 0.1727 g of an unknown gas to a 125-mL flask. If Dr. B finds the pressure to be 736 torr at 20.0°C, is the gas likely to be methane, CH₄, nitrogen, N₂, oxygen, O₂, neon, Ne, or argon, Ar?

Correct Answer
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The volume of a single molecule of water is 2.99 × 10⁻²³ mL. For a sample of gaseous water at 1.00 atm and 150°C, what fraction of the container's volume is occupied by the molecules themselves?

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A 250.0-mL sample of ammonia, NH₃(g) , exerts a pressure of 833 torr at 42.4°C. What mass of ammonia is in the container?

Correct Answer
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