Question 1

A compound is found to be 30.45% N and 69.55 % O by mass. If 1.63 g of this compound occupy 389 mL at 0.00 °C and 1.0332 bar, what is the molecular formula of the compound?

Accepted Answer

A) NO2 
B) N2O 
C) N4O2 
D) N2O5 
E) N2O4 
A) NO2 
B) N2O 
C) N4O2 
D) N2O5 
E) N2O4 E

Question 2

Determine the volume of O2 (at STP)formed when 50.0 g of KClO3 decomposes according to the following reaction. The molar mass for KClO3 is 122.55 g mol-1. 2KClO3(s)→ 2KCl(s)+ 3O2(g)

Accepted Answer

A) 9.14 L 
B) 8.22 L 
C) 12.3 L 
D) 13.9 L 
E) 14.6 L 
A) 9.14 L 
B) 8.22 L 
C) 12.3 L 
D) 13.9 L 
E) 14.6 L D

Question 3

How many moles of molecular oxygen are required to produce a pressure of 0.413 bar in a 650 mL container with a temperature of 245 K?

Accepted Answer

A) 0.0132 
B) 0.199 
C) 0.00872 
D) 0.00971 
E) 0.0245 
A) 0.0132 
B) 0.199 
C) 0.00872 
D) 0.00971 
E) 0.0245 A

Question 4

Match the following.

-barometer

Accepted Answer

A) measures blood pressure 
B) measures pressure of a gas 
C) V1/n1 = V2/n2 
D) PV = nRT 
E) P1V1 = P2V2
F)measures atmospheric pressure
G)V1/T1 = V2/T2
H)PT = PA + PB + PC ... 
A) measures blood pressure 
B) measures pressure of a gas 
C) V1/n1 = V2/n2 
D) PV = nRT 
E) P1V1 = P2V2
F)measures atmospheric pressure
G)V1/T1 = V2/T2
H)PT = PA + PB + PC ...

Question 5

The volume of a gas is proportional to the temperature of a gas. What is this known as?

Accepted Answer

A) Avogadro's law 
B) Ideal gas law 
C) Charles's law 
D) Boyle's law 
E) Dalton's law 
A) Avogadro's law 
B) Ideal gas law 
C) Charles's law 
D) Boyle's law 
E) Dalton's law

Question 6

If a sample of 0.29 moles of Ar occupies 3.8 L under certain conditions, what volume will 0.66 moles occupy under the same conditions?

Accepted Answer

A) 12 L 
B) 8.6 L 
C) 17 L 
D) 5.0 L 
E) 15 L 
A) 12 L 
B) 8.6 L 
C) 17 L 
D) 5.0 L 
E) 15 L

Question 7

A gas occupies 3.33 L at 2.23 bar. What is the volume at 2.50 bar?

Accepted Answer

A) 1.67 L 
B) 3.73 L 
C) 2.97 L 
D) 0.268 L 
E) 18.6 L 
A) 1.67 L 
B) 3.73 L 
C) 2.97 L 
D) 0.268 L 
E) 18.6 L

Question 8

Determine the theoretical yield and the percent yield if 21.8 g of K2CO3 is produced from reacting 27.9 g KO2 with 29.0 L of CO2 (at STP). The molar mass of KO2 is 71.10 g mol-1 and K2CO3 is 138.21 g mol-1. 4KO2(s)+ 2CO2(g)→ 2K2CO3(s)+ 3O2(g)

Accepted Answer

A) 27.1 g, 80.4% yield 
B) 179 g, 12.2% yield 
C) 91.7 g, 23.8% yield 
D) 206 g, 10.6% yield 
E) 61.0 g, 35.7% yield 
A) 27.1 g, 80.4% yield 
B) 179 g, 12.2% yield 
C) 91.7 g, 23.8% yield 
D) 206 g, 10.6% yield 
E) 61.0 g, 35.7% yield

Question 9

Give the formula for ozone.

Accepted Answer

A) O3 
B) O2 
C) O 
D) H2O2 
E) H2O 
A) O3 
B) O2 
C) O 
D) H2O2 
E) H2O

Question 10

Define hypoxia.

Accepted Answer

A) oxygen starvation 
B) increased oxygen concentration in body tissues 
C) increased nitrogen concentration in body tissues and fluids 
D) nitrogen starvation 
A) oxygen starvation 
B) increased oxygen concentration in body tissues 
C) increased nitrogen concentration in body tissues and fluids 
D) nitrogen starvation

Question 11

The density of a gas is 1.146 g L-1 at STP. What is the gas?

Accepted Answer

A) He 
B) O2 
C) C2H2 
D) O3 
A) He 
B) O2 
C) C2H2 
D) O3

Question 12

A syringe initially holds a sample of gas with a volume of 285 mL at 355 K and 1.88 bar. To what temperature must the gas in the syringe be heated/cooled to have a volume of 435 mL at 2.50 bar?

Accepted Answer

A) 139 K 
B) 572 K 
C) 175 K 
D) 466 K 
E) 720 K 
A) 139 K 
B) 572 K 
C) 175 K 
D) 466 K 
E) 720 K

Question 13

A 0.465 g sample of an unknown compound occupies 245 mL at 298 K and 1.24 bar. What is the molar mass of the unknown compound?

Accepted Answer

A) 26.3 g mol-1 
B) 33.9 g mol-1 
C) 12.2 g mol-1 
D) 38.0 g mol-1 
E) 81.8 g mol-1 
A) 26.3 g mol-1 
B) 33.9 g mol-1 
C) 12.2 g mol-1 
D) 38.0 g mol-1 
E) 81.8 g mol-1

Question 14

A gas mixture consists of N2, O2, and Ne, where the mole fraction of N2 is 0.55 and the mole fraction of Ne is 0.25. If the mixture is at STP in a 5.0 L container, how many molecules of O2 are present?

Accepted Answer

A) 4.5 × 1022 molecules O2 
B) 2.7 × 1022 molecules O2 
C) 3.7 × 1023 molecules O2 
D) 1.1 × 1023 molecules O2 
E) 9.3 × 1024 molecules O2 
A) 4.5 × 1022 molecules O2 
B) 2.7 × 1022 molecules O2 
C) 3.7 × 1023 molecules O2 
D) 1.1 × 1023 molecules O2 
E) 9.3 × 1024 molecules O2

Question 15

Which of the following statements is TRUE?

Accepted Answer

A) Particles of different masses have the same average speed at a given temperature. 
B) The larger a molecule, the faster it will effuse. 
C) At very high pressures, a gas will occupy a larger volume than predicted by the ideal gas law. 
D) For a given gas, the lower the temperature, the faster it will effuse. 
E) None of the above statements is true. 
A) Particles of different masses have the same average speed at a given temperature. 
B) The larger a molecule, the faster it will effuse. 
C) At very high pressures, a gas will occupy a larger volume than predicted by the ideal gas law. 
D) For a given gas, the lower the temperature, the faster it will effuse. 
E) None of the above statements is true.

Question 16

Which of the gases in the graph below has the smallest molar mass?

Accepted Answer

A) A 
B) B 
C) C 
D) D 
E) There is not enough information to determine the answer. 
A) A 
B) B 
C) C 
D) D 
E) There is not enough information to determine the answer.

Question 17

A mixture of 10.0 g of Ne and 10.0 g Ar have a total pressure of 1.6 bar. What is the partial pressure of Ne?

Accepted Answer

A) 1.1 bar 
B) 0.80 bar 
C) 0.54 bar 
D) 0.40 bar 
E) 1.3 bar 
A) 1.1 bar 
B) 0.80 bar 
C) 0.54 bar 
D) 0.40 bar 
E) 1.3 bar

Question 18

Which of the following compounds will behave LEAST like an ideal gas at low temperatures?

Accepted Answer

A) He 
B) SO2 
C) H2 
D) N2 
E) F2 
A) He 
B) SO2 
C) H2 
D) N2 
E) F2

Question 19

An unknown ideal gas was added to an evacuated 775 mL container at a temperature of 267.2 K. If 0.381 moles were added, what is the final pressure?

Accepted Answer

A) 15.8 bar 
B) 12.4 bar 
C) 9.92 bar 
D) 10.9 bar 
E) 8.92 bar 
A) 15.8 bar 
B) 12.4 bar 
C) 9.92 bar 
D) 10.9 bar 
E) 8.92 bar

Question 20

What volume will 4.91 × 1022 atoms of Ne occupy at STP?

Accepted Answer

A) 1.10 L 
B) 2.00 L 
C) 2.24 L 
D) 3.11 L 
E) 1.85 L 
A) 1.10 L 
B) 2.00 L 
C) 2.24 L 
D) 3.11 L 
E) 1.85 L

Exam 5: Gases

A compound is found to be 30.45% N and 69.55 % O by mass. If 1.63 g of this compound occupy 389 mL at 0.00 °C and 1.0332 bar, what is the molecular formula of the compound?

Determine the volume of O2 (at STP)formed when 50.0 g of KClO3 decomposes according to the following reaction. The molar mass for KClO3 is 122.55 g mol-1. 2KClO3(s)→ 2KCl(s)+ 3O2(g)

How many moles of molecular oxygen are required to produce a pressure of 0.413 bar in a 650 mL container with a temperature of 245 K?

Match the following. -barometer

The volume of a gas is proportional to the temperature of a gas. What is this known as?

If a sample of 0.29 moles of Ar occupies 3.8 L under certain conditions, what volume will 0.66 moles occupy under the same conditions?

A gas occupies 3.33 L at 2.23 bar. What is the volume at 2.50 bar?

Determine the theoretical yield and the percent yield if 21.8 g of K2CO3 is produced from reacting 27.9 g KO2 with 29.0 L of CO2 (at STP). The molar mass of KO2 is 71.10 g mol-1 and K2CO3 is 138.21 g mol-1. 4KO2(s)+ 2CO2(g)→ 2K2CO3(s)+ 3O2(g)

Give the formula for ozone.

Define hypoxia.

The density of a gas is 1.146 g L-1 at STP. What is the gas?

A syringe initially holds a sample of gas with a volume of 285 mL at 355 K and 1.88 bar. To what temperature must the gas in the syringe be heated/cooled to have a volume of 435 mL at 2.50 bar?

A 0.465 g sample of an unknown compound occupies 245 mL at 298 K and 1.24 bar. What is the molar mass of the unknown compound?

A gas mixture consists of N2, O2, and Ne, where the mole fraction of N2 is 0.55 and the mole fraction of Ne is 0.25. If the mixture is at STP in a 5.0 L container, how many molecules of O2 are present?

Which of the following statements is TRUE?

Which of the gases in the graph below has the smallest molar mass?

A mixture of 10.0 g of Ne and 10.0 g Ar have a total pressure of 1.6 bar. What is the partial pressure of Ne?

Which of the following compounds will behave LEAST like an ideal gas at low temperatures?

An unknown ideal gas was added to an evacuated 775 mL container at a temperature of 267.2 K. If 0.381 moles were added, what is the final pressure?

What volume will 4.91 × 1022 atoms of Ne occupy at STP?

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Molecules, Compounds, and Nomenclature

Chemical Reactions and Stoichiometry

Thermochemistry

The Quantum-Mechanical Model of the Atom

Periodic Properties of the Elements

Chemical Bonding I: Lewis Theory

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Determine the volume of O₂ (at STP)formed when 50.0 g of KClO₃ decomposes according to the following reaction. The molar mass for KClO₃is 122.55 g mol^-1. 2KClO₃(s)→ 2KCl(s)+ 3O₂(g)

Determine the theoretical yield and the percent yield if 21.8 g of K₂CO₃ is produced from reacting 27.9 g KO₂ with 29.0 L of CO₂ (at STP). The molar mass of KO₂ is 71.10 g mol^-1 and K₂CO₃is 138.21 g mol^-1. 4KO₂(s)+ 2CO₂(g)→ 2K₂CO₃(s)+ 3O₂(g)

The density of a gas is 1.146 g L^-1 at STP. What is the gas?

A gas mixture consists of N₂, O₂, and Ne, where the mole fraction of N₂ is 0.55 and the mole fraction of Ne is 0.25. If the mixture is at STP in a 5.0 L container, how many molecules of O₂ are present?

What volume will 4.91 × 10²²atoms of Ne occupy at STP?