Question 1

Use the van der Waals equation for real gases to calculate the pressure exerted by 1.00 mole of ammonia at 27°C in a 750-mL container. (a = 4.17 L2atm/mol2, b = 0.0371 L/mol)

Accepted Answer

A)   23.2 atm
B)   27.1 atm
C)   32.8 atm
D)   42.0 atm
E)   32.8 torrF) B) and C)
G) A) and E)

Question 2

A compound composed of carbon, hydrogen, and chlorine effuses through a pinhole 0.411 times as fast as neon. Select the correct molecular formula for the compound.

Accepted Answer

A)   CHCl3
B)   CH2Cl2
C)   C2H2Cl2
D)   C2H3Cl
E)   CCl4F) D) and E)
G) C) and E) A

Question 3

Calculate the pressure of a helium sample at -207.3°C and 768 mL if it exerts a pressure of 175 kPa at 25.0°C and 925 mL.

Accepted Answer

A)   32.1 kPa
B)   46.6 kPa
C)   657 kPa
D)   953 kPa
E)   not possible, since the pressure would have to be negativeF) A) and B)
G) None of the above B

Question 4

Select the gas with the largest root-mean-square molecular speed at 25°C.

Accepted Answer

A)   NH3
B)   CO
C)   H2
D)   SF6
E)   All the gases have the same root-mean-square molecular speed at 25°C.F) A) and C)
G) A) and B)

Question 5

"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) A) and B)
G) D) and E)

Question 6

Select the gas with the highest average kinetic energy per mole at 298 K.

Accepted Answer

A)   O2
B)   CO2
C)   H2O
D)   H2
E)   All have the same average kinetic energy.F) A) and E)
G) A) and C)

Question 7

State Boyle's Law and illustrate it with a graph, using standard x-y coordinate axes. Be sure to label the axes unambiguously with the correct gas variables.

Accepted Answer

At constant temperature, the volume of a...

Question 8

Freon-12, CF2Cl2, which has been widely used in air conditioning systems, is considered a threat to the ozone layer in the stratosphere. Calculate the root-mean-square velocity of Freon-12 molecules in the lower stratosphere where the temperature is -65°C.

Accepted Answer

A)   20 m/s
B)   120 m/s
C)   210 m/s
D)   260 m/s
E)   4.4 × 104 m/sF) C) and D)
G) B) and E) C

Question 9

"The volume of an ideal gas is directly proportional to the number of moles of the gas at constant temperature and pressure" is a statement of _____________ Law.

Accepted Answer

A)   Charles's
B)   Boyle's
C)   Amontons's
D)   Avogadro's
E)   Dalton'sF) None of the above
G) B) and C)

Question 10

"The rate of effusion of a gas is inversely proportional to the square root of its molar mass" is a statement of ______________________ Law.

Accepted Answer

A)   Charles's
B)   Graham's
C)   Dalton's
D)   Avogadro's
E)   Boyle'sF) None of the above
G) A) and B)

Question 11

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) C) and D)
G) A) and B)

Question 12

An oxygen sample of 1.62 L is at 92.3 kPa and 30.0°C.
a. What is the pressure of oxygen, in torr?
b. What volume would the oxygen occupy if the pressure were 120.0 kPa and the temperature were 0.0°C?
c. How many moles of oxygen are in the sample?

Accepted Answer

a. 692 tor...

Question 13

Calculate the density in g/L of gaseous SF6 at 50.0°C and 650. torr.

Accepted Answer

Question 14

The ideal gas law tends to become inaccurate when

Accepted Answer

A)   the pressure is lowered and molecular interactions become significant.
B)   the pressure is raised and the temperature is lowered.
C)   the temperature is raised above the temperature of STP.
D)   large gas samples are involved.
E)   the volume expands beyond the standard molar volume.F) A) and E)
G) A) and D)

Question 15

Use plots of PV/nRT versus P to show the behavior of an ideal gas and of typical real gases. Label the axes and show their scales.

Accepted Answer

Ideal gas: the plot is a horizontal line...

Question 16

A gas mixture consists of equal masses of methane (molecular weight 16.0)  and argon (atomic weight 40.0) . If the partial pressure of argon is 200. torr, what is the pressure of methane, in torr?

Accepted Answer

A)   80.0 torr
B)   200. torr
C)   256 torr
D)   500. torr
E)   556 torrF) C) and D)
G) D) and E)

Question 17

Which of the following changes will NOT affect the total pressure of gas in a container, assuming all other factors remain constant?

Accepted Answer

A)   The frequency of collisions of molecules with the walls is increased.
B)   The average velocity of the molecules is lowered.
C)   The temperature of the sample is altered.
D)   Half of the molecules are replaced by an equal number of molecules of a gas with a different molecular weight.
E)   The total number of molecules is altered.F) D) and E)
G) C) and D)

Question 18

An unknown liquid is vaporized in a 273-mL flask by immersion in a water bath at 99°C. The barometric pressure is 753 torr. If the mass of the vapor retained in the flask is 1.362 g, what is its molar mass?

Accepted Answer

A)   20.4 g/mol
B)   40.9 g/mol
C)   112 g/mol
D)   154 g/mol
E)   184 g/molF) A) and B)
G) A) and C)

Question 19

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)   CH4
B)   N2
C)   Ne
D)   Ar
E)   O2F) A) and B)
G) C) and D)

Question 20

A sample of the inert gas krypton has its pressure tripled while its temperature remained constant. If the original volume is 12 L, what is the final volume?

Accepted Answer

A)   4.0 L
B)   6.0 L
C)   9 L
D)   36 L
E)   48 LF) C) and D)
G) A) and B)

Exam 5: Gases and the Kinetic-Molecular Theory

Use the van der Waals equation for real gases to calculate the pressure exerted by 1.00 mole of ammonia at 27°C in a 750-mL container. (a = 4.17 L2atm/mol2, b = 0.0371 L/mol)

Correct AnswerverifiedShow Answer

A compound composed of carbon, hydrogen, and chlorine effuses through a pinhole 0.411 times as fast as neon. Select the correct molecular formula for the compound.

Correct AnswerverifiedA

Calculate the pressure of a helium sample at -207.3°C and 768 mL if it exerts a pressure of 175 kPa at 25.0°C and 925 mL.

Correct AnswerverifiedB

Select the gas with the largest root-mean-square molecular speed at 25°C.

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

Select the gas with the highest average kinetic energy per mole at 298 K.

Correct AnswerverifiedShow Answer

State Boyle's Law and illustrate it with a graph, using standard x-y coordinate axes. Be sure to label the axes unambiguously with the correct gas variables.

Correct AnswerverifiedAt constant temperature, the volume of a...View AnswerShow Answer

Freon-12, CF2Cl2, which has been widely used in air conditioning systems, is considered a threat to the ozone layer in the stratosphere. Calculate the root-mean-square velocity of Freon-12 molecules in the lower stratosphere where the temperature is -65°C.

Correct AnswerverifiedC

"The volume of an ideal gas is directly proportional to the number of moles of the gas at constant temperature and pressure" is a statement of _____________ Law.

Correct AnswerverifiedShow Answer

"The rate of effusion of a gas is inversely proportional to the square root of its molar mass" 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?

Correct AnswerverifiedShow Answer

An oxygen sample of 1.62 L is at 92.3 kPa and 30.0°C. a. What is the pressure of oxygen, in torr? b. What volume would the oxygen occupy if the pressure were 120.0 kPa and the temperature were 0.0°C? c. How many moles of oxygen are in the sample?

Correct Answerverifieda. 692 tor...View AnswerShow Answer

Calculate the density in g/L of gaseous SF6 at 50.0°C and 650. torr.

Correct AnswerverifiedShow Answer

The ideal gas law tends to become inaccurate when

Correct AnswerverifiedShow Answer

Use plots of PV/nRT versus P to show the behavior of an ideal gas and of typical real gases. Label the axes and show their scales.

Correct AnswerverifiedIdeal gas: the plot is a horizontal line...View AnswerShow Answer

A gas mixture consists of equal masses of methane (molecular weight 16.0) and argon (atomic weight 40.0) . If the partial pressure of argon is 200. torr, what is the pressure of methane, in torr?

Correct AnswerverifiedShow Answer

Which of the following changes will NOT affect the total pressure of gas in a container, assuming all other factors remain constant?

Correct AnswerverifiedShow Answer

An unknown liquid is vaporized in a 273-mL flask by immersion in a water bath at 99°C. The barometric pressure is 753 torr. If the mass of the vapor retained in the flask is 1.362 g, what is its molar mass?

Correct AnswerverifiedShow Answer

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

A sample of the inert gas krypton has its pressure tripled while its temperature remained constant. If the original volume is 12 L, what is the final volume?

Correct AnswerverifiedShow Answer

Use the van der Waals equation for real gases to calculate the pressure exerted by 1.00 mole of ammonia at 27°C in a 750-mL container. (a = 4.17 L²atm/mol², b = 0.0371 L/mol)

Correct Answer
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A

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B

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At constant temperature, the volume of a...
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Freon-12, CF₂Cl₂, which has been widely used in air conditioning systems, is considered a threat to the ozone layer in the stratosphere. Calculate the root-mean-square velocity of Freon-12 molecules in the lower stratosphere where the temperature is -65°C.

Correct Answer
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C

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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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a. 692 tor...
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Calculate the density in g/L of gaseous SF₆ at 50.0°C and 650. torr.

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Ideal gas: the plot is a horizontal line...
View 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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Correct Answer
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