Question 1

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 L A

Question 2

A sample of carbon dioxide gas at 125°C and 248 torr occupies a volume of 275 L. What will the gas pressure be if the volume is increased to 321 L at 125°C?

Accepted Answer

A)  212 torr
B)  289 torr
C)  356 torr
D)  441 torr
E)  359 torr

Question 3

A gas mixture, with a total pressure of 300. torr, consists of equal masses of Ne (atomic weight 20.)  and Ar (atomic weight 40.) . What is the partial pressure of Ar, in torr?

Accepted Answer

A)  75 torr
B)  100. torr
C)  150. torr
D)  200. torr
E)  None of these choices are correct.

Question 4

The most probable speed of an oxygen molecule in the gas phase at room temperature is 450 m/s. The root-mean-square speed (urms)  is therefore

Accepted Answer

A)  equal to 450 m/s.
B)  slightly less than 450 m/s.
C)  much less than 450 m/s.
D)  slightly greater than 450 m/s.
E)  much greater than 450 m/s.

Question 5

Select the statement that does not apply to an ideal gas.

Accepted Answer

A)  There are no attractive forces between the gas molecules.
B)  There are strong repulsive forces between the gas molecules.
C)  The volume occupied by the molecules is negligible compared to the container volume.
D)  The gas behaves according to the ideal gas equation.
E)  The average kinetic energy of the molecules is proportional to the absolute temperature.

Question 6

A 500-mL sample of argon at 800 torr has its absolute temperature quadrupled. If the volume remains unchanged what is the new pressure?

Accepted Answer

A)  200 torr
B)  400 torr
C)  800 torr
D)  2400 torr
E)  3200 torr

Question 7

For a gas obeying Boyle's Law, a plot of V versus 1/P will give a straight line passing through the origin.

Accepted Answer

A) True 
 B)False  True

Question 8

For a gas obeying Charles's Law, a plot of V versus 1/T will give a straight line passing through the origin.

Accepted Answer

A) True 
 B)False

Question 9

A sample container of carbon monoxide occupies a volume of 435 mL at a pressure of 785 torr and a temperature of 298 K. What would its temperature be if the volume were changed to 265 mL at a pressure of 785 torr?

Accepted Answer

A)  182 K
B)  298 K
C)  387 K
D)  489 K
E)  538 K A

Question 10

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

Accepted Answer

A) True 
 B)False

Question 11

A weather balloon was initially at a pressure of 0.950 atm, and its volume was 35.0 L. The pressure decreased to 0.750 atm, without loss of gas or change in temperature. What was the change in the volume?

Accepted Answer

A)  Increased by 44.3 L
B)  Increased by 9.3 L
C)  Increased by 7.4 L
D)  Decreased by 27.6 L
E)  Decreased by 7.4 L

Question 12

Given that pressure has dimensions of force ÷ area; that force has dimensions of mass × acceleration; and that the S.I. unit of pressure is the pascal, what is 1 pascal in terms of S.I. base units?

Accepted Answer

A)  1 Pa = 1000 g/cm·s 2
B)  1 Pa = 1 g/m·s 2
C)  1 Pa = 10 −3 kg·m/s 2
D)  1 Pa = 1 kg·m/s 2
E)  1 Pa = 1 kg/m·s 2

Question 13

Ima Chemist found the density of Freon-11 (CFCl3)  to be 5.58 g/L under her experimental conditions. Her measurements showed that the density of an unknown gas was 4.38 g/L under the same conditions. What is the molar mass of the unknown?

Accepted Answer

A)  96.7 g/mol
B)  108 g/mol
C)  127 g/mol
D)  165 g/mol
E)  175 g/mol

Question 14

Calculate the rms speed of carbon dioxide molecules at STP.

Accepted Answer

A)  12.4 m/s
B)  155 m/s
C)  393 m/s
D)  1.55 × 10 5 m/s
E)  The answer can't be calculated without more data.

Question 15

A sample of oxygen gas has its absolute temperature halved while the pressure of the gas remained constant. If the initial volume is 400 mL, what is the final volume?

Accepted Answer

A)  20 mL
B)  133 mL
C)  200 mL
D)  400 mL
E)  800 mL

Question 16

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

Accepted Answer

A)  Charles's
B)  Boyle's
C)  Amontons's
D)  Avogadro's
E)  Dalton's

Question 17

For real gases, PV < nRT, always.

Accepted Answer

A) True 
 B)False

Question 18

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 torr

Question 19

A sample of nitrogen gas is confined to a 14.0 L container at 375 torr and 37.0°C. How many moles of nitrogen are in the container?

Accepted Answer

A)  0.271 mol
B)  2.27 mol
C)  3.69 mol
D)  206 mol
E)  227 mol

Question 20

Calculate the temperature of an argon sample at 55.4 kPa and 18.6 L if it occupies 25.8 L at 75.0°C and 41.1 kPa.

Accepted Answer

A)  95.0°C
B)  85.1°C
C)  77.2°C
D)  72.9°C
E)  65.2°C

Exam 5: Gases and the Kinetic-Molecular Theory

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 AnswerverifiedA

A sample of carbon dioxide gas at 125°C and 248 torr occupies a volume of 275 L. What will the gas pressure be if the volume is increased to 321 L at 125°C?

Correct AnswerverifiedShow Answer

A gas mixture, with a total pressure of 300. torr, consists of equal masses of Ne (atomic weight 20.) and Ar (atomic weight 40.) . What is the partial pressure of Ar, in torr?

Correct AnswerverifiedShow Answer

The most probable speed of an oxygen molecule in the gas phase at room temperature is 450 m/s. The root-mean-square speed (urms) is therefore

Correct AnswerverifiedShow Answer

Select the statement that does not apply to an ideal gas.

Correct AnswerverifiedShow Answer

A 500-mL sample of argon at 800 torr has its absolute temperature quadrupled. If the volume remains unchanged what is the new pressure?

Correct AnswerverifiedShow Answer

For a gas obeying Boyle's Law, a plot of V versus 1/P will give a straight line passing through the origin.

Correct AnswerverifiedTrue

For a gas obeying Charles's Law, a plot of V versus 1/T will give a straight line passing through the origin.

Correct AnswerverifiedShow Answer

A sample container of carbon monoxide occupies a volume of 435 mL at a pressure of 785 torr and a temperature of 298 K. What would its temperature be if the volume were changed to 265 mL at a pressure of 785 torr?

Correct AnswerverifiedA

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

Correct AnswerverifiedShow Answer

A weather balloon was initially at a pressure of 0.950 atm, and its volume was 35.0 L. The pressure decreased to 0.750 atm, without loss of gas or change in temperature. What was the change in the volume?

Correct AnswerverifiedShow Answer

Given that pressure has dimensions of force ÷ area; that force has dimensions of mass × acceleration; and that the S.I. unit of pressure is the pascal, what is 1 pascal in terms of S.I. base units?

Correct AnswerverifiedShow Answer

Ima Chemist found the density of Freon-11 (CFCl3) to be 5.58 g/L under her experimental conditions. Her measurements showed that the density of an unknown gas was 4.38 g/L under the same conditions. What is the molar mass of the unknown?

Correct AnswerverifiedShow Answer

Calculate the rms speed of carbon dioxide molecules at STP.

Correct AnswerverifiedShow Answer

A sample of oxygen gas has its absolute temperature halved while the pressure of the gas remained constant. If the initial volume is 400 mL, what is the final volume?

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

For real gases, PV < nRT, always.

Correct AnswerverifiedShow 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

A sample of nitrogen gas is confined to a 14.0 L container at 375 torr and 37.0°C. How many moles of nitrogen are in the container?

Correct AnswerverifiedShow Answer

Calculate the temperature of an argon sample at 55.4 kPa and 18.6 L if it occupies 25.8 L at 75.0°C and 41.1 kPa.

Correct AnswerverifiedShow Answer

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The most probable speed of an oxygen molecule in the gas phase at room temperature is 450 m/s. The root-mean-square speed (u_rms) is therefore

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Ima Chemist found the density of Freon-11 (CFCl₃) to be 5.58 g/L under her experimental conditions. Her measurements showed that the density of an unknown gas was 4.38 g/L under the same conditions. What is the molar mass of the unknown?

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