Question 1

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

Question 2

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 L 
A) 21.8 L 
B) 27.6 L 
C) 29.6 L 
D) 37.6 L 
E) 153 L

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. 
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.

Question 4

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. 
A) −50. torr 
B) 50. torr 
C) 695 torr 
D) 795 torr 
E) None of these choices are correct.

Question 5

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

Question 6

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

Question 7

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

Question 8

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

Question 9

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

Question 10

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 2 
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 2

Question 11

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. 
A) −230. 
B) 230. 
C) 530. 
D) 790. 
E) None of these choices are correct.

Question 12

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

Question 14

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

Question 15

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

Question 16

"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's 
A) Charles's 
B) Boyle's 
C) Amontons's 
D) Avogadro's 
E) Gay-Lussac's

Question 17

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

Question 18

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. 
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.

Question 19

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

Question 20

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) e 
A) a 
B) b 
C) c 
D) d 
E) e

Exam 5: Gases and the Kinetic-Molecular Theory

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?

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?

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?

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?

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?

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

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?

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?

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

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)

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?

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

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?

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?

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

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

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)

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

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?

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?

Keys to the Study of Chemistry: Definitions, Units, and Problem Solving

The Components of Matter

Stoichiometry of Formulas and Equations

Three Major Classes of Chemical Reactions

Thermochemistry: Energy Flow and Chemical Change

Quantum Theory and Atomic Structure

Electron Configuration and Chemical Periodicity

Models of Chemical Bonding

The Shapes of Molecules

Theories of Covalent Bonding

Intermolecular Forces: Liquids, Solids, and Phase Changes

The Properties of Mixtures: Solutions and Colloids

Periodic Patterns in the Main-Group Elements

Organic Compounds and the Atomic Properties of Carbon

Kinetics: Rates and Mechanisms of Chemical Reactions

Equilibrium: the Extent of Chemical Reactions

Acid-Base Equilibria

Ionic Equilibria in Aqueous Systems

Thermodynamics: Entropy, Free Energy, and Reaction Direction

Electrochemistry: Chemical Change and Electrical Work

The Elements in Nature and Industry

Transition Elements and Their Coordination Compounds

Nuclear Reactions and Their Applications

Filters

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?

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?

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)

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?

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)

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?