Question 1

Calculate the root-mean-square speed of methane,CH4(g),at 78°C.

Accepted Answer

A) 23 m/s 
B) 350 m/s 
C) 550 m/s 
D) 667 m/s 
E) 739 m/s 
A) 23 m/s 
B) 350 m/s 
C) 550 m/s 
D) 667 m/s 
E) 739 m/s

Question 2

What is the initial pressure of a gas having an initial temperature of 905 K,an initial volume of 14.3 L,a final pressure of 0.83 atm,a final temperature of 154 K and a final volume of 2.7 L?

Accepted Answer

A) 26 atm 
B) 0.27 atm 
C) 0.75 atm 
D) 1.3 atm 
E) 0.92 atm 
A) 26 atm 
B) 0.27 atm 
C) 0.75 atm 
D) 1.3 atm 
E) 0.92 atm

Question 3

The mole fraction of oxygen molecules in dry air is 0.2095.What volume of dry air at 1.00 atm and 25°C is required for burning completely 1.00 L of octane (C8H18,density = 0.7025 g/mL),yielding carbon dioxide and water? (R = 0.08206 L • atm/K • mol)

Accepted Answer

A) 394 L 
B) 1880 L 
C) 8220 L 
D) 8970 L 
E) 17,900 L 
A) 394 L 
B) 1880 L 
C) 8220 L 
D) 8970 L 
E) 17,900 L

Question 4

What are the conditions of STP?

Accepted Answer

A) 0 K and 1 atm 
B) 273.15 K and 760 torr 
C) 0°C and 760 atm 
D) 273.15°C and 760 torr 
E) 0°C and 1 torr 
A) 0 K and 1 atm 
B) 273.15 K and 760 torr 
C) 0°C and 760 atm 
D) 273.15°C and 760 torr 
E) 0°C and 1 torr

Question 5

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.torr 
B) 230.torr 
C) 530.torr 
D) 790.torr 
E) 990.torr 
A) -230.torr 
B) 230.torr 
C) 530.torr 
D) 790.torr 
E) 990.torr

Question 6

A gas evolved during the fermentation of sugar was collected at 22.5°C and 702 mmHg.After purification its volume was found to be 25.0 L.How many moles of gas were collected? (R = 0.08206 L • atm/K • mol,1 atm = 760 mmHg)

Accepted Answer

A) 0.952 mol 
B) 1.05 mol 
C) 12.5 mol 
D) 22.4 mol 
E) 724 mol 
A) 0.952 mol 
B) 1.05 mol 
C) 12.5 mol 
D) 22.4 mol 
E) 724 mol

Question 7

The temperature of the carbon dioxide atmosphere near the surface of Venus is 475°C.Calculate the average kinetic energy per mole of carbon dioxide molecules on Venus.

Accepted Answer

A) 2520 J/mol 
B) 4150 J/mol 
C) 5920 J/mol 
D) 9330 J/mol 
E) 5920 kJ/mol 
A) 2520 J/mol 
B) 4150 J/mol 
C) 5920 J/mol 
D) 9330 J/mol 
E) 5920 kJ/mol

Question 8

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

Question 9

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

Question 10

What volume of chlorine gas at 25°C and 0.950 atm can be produced by the reaction of 12.0 g of MnO2 in excess HCl(aq)? MnO2(s)+ 4HCl(aq)→ MnCl2(aq)+ 2H2O(l)+ Cl2(g)
(R = 0.08206 L • atm/K • mol)

Accepted Answer

A) 5.36 × 10-3 L 
B) 0.138 L 
C) 0.282 L 
D) 3.09 L 
E) 3.55 L 
A) 5.36 × 10-3 L 
B) 0.138 L 
C) 0.282 L 
D) 3.09 L 
E) 3.55 L

Question 11

What is the mass,in grams,of 2.74 L of CO gas measured at 33°C and 945 mmHg? (R = 0.08206 L • atm/mol • K,1 atm = 760 mmHg)

Accepted Answer

A) 0.263 g 
B) 2.46 g 
C) 3.80 g 
D) 35.2 g 
E) 206 g 
A) 0.263 g 
B) 2.46 g 
C) 3.80 g 
D) 35.2 g 
E) 206 g

Question 12

"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 13

A sample of a gas has an initial pressure of 0.987 atm and a volume of 12.8 L.What is the final pressure if the volume is increased to 25.6 L?

Accepted Answer

A) 2.03 atm 
B) 1.97 atm 
C) 0.494 atm 
D) 0.003 atm 
E) 323.4 atm 
A) 2.03 atm 
B) 1.97 atm 
C) 0.494 atm 
D) 0.003 atm 
E) 323.4 atm

Question 14

A sample of nitrogen gas at 298 K and 745 torr has a volume of 37.42 L.What volume will it occupy if the pressure is increased to 894 torr at constant temperature?

Accepted Answer

A) 22.3 L 
B) 31.2 L 
C) 44.9 L 
D) 112 L 
E) 380 L 
A) 22.3 L 
B) 31.2 L 
C) 44.9 L 
D) 112 L 
E) 380 L

Question 15

Magnesium metal (0.100 mol)and hydrochloric acid (0.500 mol HCl)are combined and react to completion. What volume of hydrogen gas,measured at STP,is produced?
Mg(s)+ 2HCl(aq)→ MgCl2(aq)+ H2(g)
(R = 0.08206 L • atm/K • mol)

Accepted Answer

A) 2.24 L of H2 
B) 4.48 L of H2 
C) 5.60 L of H2 
D) 11.2 L of H2 
E) 22.4 L of H2 
A) 2.24 L of H2 
B) 4.48 L of H2 
C) 5.60 L of H2 
D) 11.2 L of H2 
E) 22.4 L of H2

Question 16

A fixed quantity of gas has a pressure of 1.35 atm,a volume of 23.8 L,and a temperature of 205.1 K.If the pressure increases to 2.84 atm and the temperature rises to 233.4 K,what is the new volume of the gas?

Accepted Answer

A) 0.183 L 
B) 7.06 L 
C) 9.94 L 
D) 12.9 L 
E) 57.0 L 
A) 0.183 L 
B) 7.06 L 
C) 9.94 L 
D) 12.9 L 
E) 57.0 L

Question 17

At very high pressures (~1000 atm),the measured pressure exerted by real gases is greater than that predicted by the ideal gas equation.This is mainly because

Accepted Answer

A) such high pressures cannot be accurately measured. 
B) real gases will condense to form liquids at 1000 atm pressure. 
C) gas phase collisions prevent molecules from colliding with the walls of the container. 
D) of attractive intermolecular forces between gas molecules. 
E) the volume occupied by the gas molecules themselves becomes significant. 
A) such high pressures cannot be accurately measured. 
B) real gases will condense to form liquids at 1000 atm pressure. 
C) gas phase collisions prevent molecules from colliding with the walls of the container. 
D) of attractive intermolecular forces between gas molecules. 
E) the volume occupied by the gas molecules themselves becomes significant.

Question 18

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 5.0 cm 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) 745 torr 
E) 795 torr 
A) -50.torr 
B) 50.torr 
C) 695 torr 
D) 745 torr 
E) 795 torr

Question 19

A gas cylinder containing 1.50 mol compressed methane has a volume of 3.30 L.What pressure does the methane exert on the walls of the cylinder if its temperature is 25°C? (R = 0.08206 L • atm/K • mol)

Accepted Answer

A) 9.00 × 10-2 atm 
B) 0.933 atm 
C) 1.11 atm 
D) 1.70 atm 
E) 11.1 atm 
A) 9.00 × 10-2 atm 
B) 0.933 atm 
C) 1.11 atm 
D) 1.70 atm 
E) 11.1 atm

Question 20

A 3.0-L sample of helium was placed in 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

Exam 10: Gases

Calculate the root-mean-square speed of methane,CH4(g),at 78°C.

What is the initial pressure of a gas having an initial temperature of 905 K,an initial volume of 14.3 L,a final pressure of 0.83 atm,a final temperature of 154 K and a final volume of 2.7 L?

The mole fraction of oxygen molecules in dry air is 0.2095.What volume of dry air at 1.00 atm and 25°C is required for burning completely 1.00 L of octane (C8H18,density = 0.7025 g/mL),yielding carbon dioxide and water? (R = 0.08206 L • atm/K • mol)

What are the conditions of STP?

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?

A gas evolved during the fermentation of sugar was collected at 22.5°C and 702 mmHg.After purification its volume was found to be 25.0 L.How many moles of gas were collected? (R = 0.08206 L • atm/K • mol,1 atm = 760 mmHg)

The temperature of the carbon dioxide atmosphere near the surface of Venus is 475°C.Calculate the average kinetic energy per mole of carbon dioxide molecules on Venus.

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

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

What volume of chlorine gas at 25°C and 0.950 atm can be produced by the reaction of 12.0 g of MnO2 in excess HCl(aq)? MnO2(s)+ 4HCl(aq)→ MnCl2(aq)+ 2H2O(l)+ Cl2(g) (R = 0.08206 L • atm/K • mol)

What is the mass,in grams,of 2.74 L of CO gas measured at 33°C and 945 mmHg? (R = 0.08206 L • atm/mol • K,1 atm = 760 mmHg)

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

A sample of a gas has an initial pressure of 0.987 atm and a volume of 12.8 L.What is the final pressure if the volume is increased to 25.6 L?

A sample of nitrogen gas at 298 K and 745 torr has a volume of 37.42 L.What volume will it occupy if the pressure is increased to 894 torr at constant temperature?

Magnesium metal (0.100 mol)and hydrochloric acid (0.500 mol HCl)are combined and react to completion. What volume of hydrogen gas,measured at STP,is produced? Mg(s)+ 2HCl(aq)→ MgCl2(aq)+ H2(g) (R = 0.08206 L • atm/K • mol)

A fixed quantity of gas has a pressure of 1.35 atm,a volume of 23.8 L,and a temperature of 205.1 K.If the pressure increases to 2.84 atm and the temperature rises to 233.4 K,what is the new volume of the gas?

At very high pressures (~1000 atm),the measured pressure exerted by real gases is greater than that predicted by the ideal gas equation.This is mainly because

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 5.0 cm below that in the arm connected to the flask of neon.What is the neon pressure,in torr?

A gas cylinder containing 1.50 mol compressed methane has a volume of 3.30 L.What pressure does the methane exert on the walls of the cylinder if its temperature is 25°C? (R = 0.08206 L • atm/K • mol)

A 3.0-L sample of helium was placed in 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?

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Calculate the root-mean-square speed of methane,CH₄(g),at 78°C.

The mole fraction of oxygen molecules in dry air is 0.2095.What volume of dry air at 1.00 atm and 25°C is required for burning completely 1.00 L of octane (C₈H₁₈,density = 0.7025 g/mL),yielding carbon dioxide and water? (R = 0.08206 L • atm/K • mol)

What volume of chlorine gas at 25°C and 0.950 atm can be produced by the reaction of 12.0 g of MnO₂ in excess HCl(aq)? MnO₂(s)+ 4HCl(aq)→ MnCl₂(aq)+ 2H₂O(l)+ Cl₂(g) (R = 0.08206 L • atm/K • mol)

Magnesium metal (0.100 mol)and hydrochloric acid (0.500 mol HCl)are combined and react to completion. What volume of hydrogen gas,measured at STP,is produced? Mg(s)+ 2HCl(aq)→ MgCl₂(aq)+ H₂(g) (R = 0.08206 L • atm/K • mol)