Question 1

What volume (L)  of H2 is formed at STP when 6.0 g of Al is treated with excess NaOH
2NaOH + 2Al + 6H2O  →\rarr→  2NaAl(OH) 4 + 3H2(g)

Accepted Answer

A)   6.5 L
B)   7.5 L
C)   8.5 L
D)   9.5 L
E)   None of the above

Question 2

What is the pressure (in atmospheres)  of the sample of gas trapped in the closed-tube mercury manometer shown below if h = 23.6 cm

Accepted Answer

A)   0.211 atm
B)   0.311 atm
C)   0.411atm
D)   0.511atm
E)   None of the above B

Question 3

Calculate the molar mass of a gaseous substance if 0.125 g of the gas occupies 93.3 mL at STP.

Accepted Answer

A)   30.0 g/mol
B)   30.2 g/mol
C)   30.4g/mol
D)   30.6 g/mol
E)   None of the above

Question 4

Calculate the number of moles of gas contained in a 10.0 L tank at 22 ∘\circ∘ C and 105 atm. (R = 0.08206 L.atm/K.mol)

Accepted Answer

A)   1.71 * 10-3 mol
B)   0.0231 mol
C)   1.03 mol
D)   43.4 mol
E)   582 mol

Question 5

An aerosol can with a volume of 0.50 L has a bursting point of 2.6 atm. If the can contains 1.0 g CO2 and is heated to 400$\circ$C, it will burst.

Accepted Answer

A) True 
 B)False

Question 6

At constant pressure, the density of a gas increases with an increase in temperature.

Accepted Answer

A) True 
 B)False

Question 7

What volume of sulfur dioxide gas at 45 ∘\circ∘ C and 723 mmHg will react completely with 0.870 L of oxygen gas at constant temperature and pressure?
2 SO2(g)  + O2(g)   →\rarr→  2SO3(g)

Accepted Answer

A)   0.0317 L
B)   0.0634 L
C)   0.870 L
D)   1.74 L
E)   3.48 L

Question 8

Which one of the following is not an example of an element that occurs as a gas at room temperature and pressure

Accepted Answer

A)   Helium
B)   Neon
C)   Chlorine
D)   Bromine
E)   Nitrogen

Question 9

What is the molar mass of Freon-11 gas if its density is 6.13 g/L at STP

Accepted Answer

A)   0.274 g/mol
B)   3.64 g/mol
C)   78.2 g/mol
D)   137 g/mol
E)   365 g/mol

Question 10

When active metals such as magnesium are immersed in acid solution, hydrogen gas is evolved. Calculate the volume of H2(g)  at 30.1 ∘\circ∘ C and 0.85 atm that can be formed when 275 mL of 0.725 M HCl solution reacts with excess Mg to give hydrogen gas and aqueous magnesium chloride.

Accepted Answer

A)   3.4 * 10-3 L
B)   2.2 L
C)   2.9 L
D)   5.8 L
E)   11.7 L

Question 11

If equal masses of O2(g)  and HBr(g)  are in separate containers of equal volume and temperature, which one of these statements is true

Accepted Answer

A)   The pressure in the O2 container is greater than that in the HBr container.
B)   There are more HBr molecules than O2 molecules.
C)   The average velocity of the O2 molecules is less than that of the HBr molecules.
D)   The average kinetic energy of HBr molecules is greater than that of O2 molecules.
E)   The pressures of both gases are the same.

Question 12

Phosgene, a chemical warfare agent used in World War I, consists of 12.41% C, 16.17% O, and 71.69% Cl. 1.00 L of this gas at STP has a mass of 4.42 g. What is the molecular formula of phosgene

Accepted Answer

A)   COCl
B)   C2OCl2
C)   COCl3
D)   COCl2
E)   None of the above

Question 13

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

Accepted Answer

A)   150 L
B)   367 L
C)   718 L
D)   1880 L
E)   8970 L

Question 14

A 0.271 g sample of an unknown vapor occupies 294 mL at 140. ∘\circ∘ C and 847 mmHg. The empirical formula of the compound is CH2. What is the molecular formula of the compound

Accepted Answer

A)   CH2
B)   C2H4
C)   C3H6
D)   C4H8
E)   C6H12  B

Question 15

Samples of the following volatile liquids are opened simultaneously at one end of a room. If you are standing at the opposite end of this room, which species would you smell first (Assume that your nose is equally sensitive to all these species.)

Accepted Answer

A)   ethyl acetate (CH3COOC2H5) 
B)   camphor (C10H16O) 
C)   diethyl ether (C2H5OC2H5) 
D)   naphthalene (C10H8) 
E)   pentanethiol (C5H11SH)

Question 16

Which statement is false

Accepted Answer

A)   The average kinetic energies of molecules from samples of different "ideal" gases are the same at the same temperature.
B)   The molecules of an ideal gas are relatively far apart.
C)   All molecules of an ideal gas have the same kinetic energy at constant temperature.
D)   Molecules of a gas undergo many collisions with each other and the container walls.
E)   Molecules of greater mass have a lower average speed than those of less mass at the same temperature. C

Question 17

If the pressure of a gas sample is tripled and the absolute temperature is quadrupled, by what factor will the volume of the sample change

Accepted Answer

A)   12
B)   4/3
C)   3/4
D)   1/3
E)   4

Question 18

The temperature of a sample of argon gas in a 365 mL container at 740. mmHg and 25 ∘\circ∘ C is lowered to 12 ∘\circ∘ C. Assuming the volume of the container and the amount of gas is unchanged, calculate the new pressure of the argon.

Accepted Answer

A)   0.468 atm
B)   0.931 atm
C)   1.02 atm
D)   1.54 atm
E)   2.03 atm

Question 19

What will happen to the height (h)  of the column of mercury in the manometer shown below if the stopcock is opened

Accepted Answer

A)   h will decrease
B)   h will not change
C)   h will increase
D)   not enough information given to answer the question

Question 20

The van der Waals equation is a modification of the ideal gas equation. What two factors does this equation account for

Accepted Answer

A)   (1)  Real gas molecules exert forces on each other. (2)  Gas molecules have energy.
B)   (1)  Real gas molecules exert ionic forces on each other. (2)  Gas molecules have energy
C)   (1)  Real gas molecules exert forces on each other. (2)  Gas molecules have volume.
D)   (1)  Real gas molecules exert ionic forces on each other. (2)  Gas molecules have volume.
E)   None of the above have BOTH of the two factors accurately stated

Exam 5: Gases

What volume (L) of H2 is formed at STP when 6.0 g of Al is treated with excess NaOH 2NaOH + 2Al + 6H2O →\rarr→ 2NaAl(OH) 4 + 3H2(g)

Correct AnswerverifiedShow Answer

What is the pressure (in atmospheres) of the sample of gas trapped in the closed-tube mercury manometer shown below if h = 23.6 cm

Correct AnswerverifiedB

Calculate the molar mass of a gaseous substance if 0.125 g of the gas occupies 93.3 mL at STP.

Correct AnswerverifiedShow Answer

Calculate the number of moles of gas contained in a 10.0 L tank at 22 ∘\circ∘ C and 105 atm. (R = 0.08206 L.atm/K.mol)

Correct AnswerverifiedShow Answer

An aerosol can with a volume of 0.50 L has a bursting point of 2.6 atm. If the can contains 1.0 g CO2 and is heated to 400 ∘\circ∘ C, it will burst.

Correct AnswerverifiedShow Answer

At constant pressure, the density of a gas increases with an increase in temperature.

Correct AnswerverifiedShow Answer

What volume of sulfur dioxide gas at 45 ∘\circ∘ C and 723 mmHg will react completely with 0.870 L of oxygen gas at constant temperature and pressure? 2 SO2(g) + O2(g) →\rarr→ 2SO3(g)

Correct AnswerverifiedShow Answer

Which one of the following is not an example of an element that occurs as a gas at room temperature and pressure

Correct AnswerverifiedShow Answer

What is the molar mass of Freon-11 gas if its density is 6.13 g/L at STP

Correct AnswerverifiedShow Answer

When active metals such as magnesium are immersed in acid solution, hydrogen gas is evolved. Calculate the volume of H2(g) at 30.1 ∘\circ∘ C and 0.85 atm that can be formed when 275 mL of 0.725 M HCl solution reacts with excess Mg to give hydrogen gas and aqueous magnesium chloride.

Correct AnswerverifiedShow Answer

If equal masses of O2(g) and HBr(g) are in separate containers of equal volume and temperature, which one of these statements is true

Correct AnswerverifiedShow Answer

Phosgene, a chemical warfare agent used in World War I, consists of 12.41% C, 16.17% O, and 71.69% Cl. 1.00 L of this gas at STP has a mass of 4.42 g. What is the molecular formula of phosgene

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

A 0.271 g sample of an unknown vapor occupies 294 mL at 140. ∘\circ∘ C and 847 mmHg. The empirical formula of the compound is CH2. What is the molecular formula of the compound

Correct AnswerverifiedB

Samples of the following volatile liquids are opened simultaneously at one end of a room. If you are standing at the opposite end of this room, which species would you smell first (Assume that your nose is equally sensitive to all these species.)

Correct AnswerverifiedShow Answer

Which statement is false

Correct AnswerverifiedC

If the pressure of a gas sample is tripled and the absolute temperature is quadrupled, by what factor will the volume of the sample change

Correct AnswerverifiedShow Answer

The temperature of a sample of argon gas in a 365 mL container at 740. mmHg and 25 ∘\circ∘ C is lowered to 12 ∘\circ∘ C. Assuming the volume of the container and the amount of gas is unchanged, calculate the new pressure of the argon.

Correct AnswerverifiedShow Answer

What will happen to the height (h) of the column of mercury in the manometer shown below if the stopcock is opened

Correct AnswerverifiedShow Answer

The van der Waals equation is a modification of the ideal gas equation. What two factors does this equation account for

Correct AnswerverifiedShow Answer

What volume (L) of H₂ is formed at STP when 6.0 g of Al is treated with excess NaOH 2NaOH + 2Al + 6H₂O $\rarr$ 2NaAl(OH) ₄ + 3H₂(g)

Correct Answer
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Correct Answer
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B

Correct Answer
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Calculate the number of moles of gas contained in a 10.0 L tank at 22^$\circ$C and 105 atm. (R = 0.08206 L.atm/K.mol)

Correct Answer
verified

An aerosol can with a volume of 0.50 L has a bursting point of 2.6 atm. If the can contains 1.0 g CO₂ and is heated to 400^$\circ$C, it will burst.

Correct Answer
verified

Correct Answer
verified

What volume of sulfur dioxide gas at 45^$\circ$C and 723 mmHg will react completely with 0.870 L of oxygen gas at constant temperature and pressure? 2 SO₂(g) + O₂(g) $\rarr$ 2SO₃(g)

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

When active metals such as magnesium are immersed in acid solution, hydrogen gas is evolved. Calculate the volume of H₂(g) at 30.1^$\circ$C and 0.85 atm that can be formed when 275 mL of 0.725 M HCl solution reacts with excess Mg to give hydrogen gas and aqueous magnesium chloride.

Correct Answer
verified

If equal masses of O₂(g) and HBr(g) are in separate containers of equal volume and temperature, which one of these statements is true

Correct Answer
verified

Correct Answer
verified

The mole fraction of oxygen molecules in dry air is 0.2095. What volume of dry air at 1.00 atm and 25^$\circ$C is required for burning 1.00 L of octane (C₈H₁₈, density = 0.7025 g/mL) completely, yielding carbon dioxide and water

Correct Answer
verified

A 0.271 g sample of an unknown vapor occupies 294 mL at 140.^$\circ$C and 847 mmHg. The empirical formula of the compound is CH₂. What is the molecular formula of the compound

Correct Answer
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B

Correct Answer
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Correct Answer
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C

Correct Answer
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The temperature of a sample of argon gas in a 365 mL container at 740. mmHg and 25^$\circ$C is lowered to 12^$\circ$C. Assuming the volume of the container and the amount of gas is unchanged, calculate the new pressure of the argon.

Correct Answer
verified

Correct Answer
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Correct Answer
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