Question 1

What is the mass in grams of 9.76 × 1012 atoms of naturally occurring potassium?

Accepted Answer

A) 2.41 × 1012 
B) 2.50 × 1011 
C) 6.34 × 10-10 
D) 1.62 × 10-11 
E) 3.82 × 1014 
A) 2.41 × 1012 
B) 2.50 × 1011 
C) 6.34 × 10-10 
D) 1.62 × 10-11 
E) 3.82 × 1014

Question 2

A compound contains 40.0% C, 6.71% H, and 53.29% O by mass. The molecular weight of the compound is 60.05 amu. The molecular formula of this compound is ________.

Accepted Answer

A) C2H4O2 
B) CH2O 
C) C2H3O4 
D) C2H2O4 
E) CHO2 
A) C2H4O2 
B) CH2O 
C) C2H3O4 
D) C2H2O4 
E) CHO2

Question 3

There are ________ oxygen atoms in 30 molecules of C20H42S3O2.

Accepted Answer

A) 6.0 × 1023 
B) 1.8 × 1025 
C) 3.6 × 1025 
D) 1.2 × 1024 
E) 60 
A) 6.0 × 1023 
B) 1.8 × 1025 
C) 3.6 × 1025 
D) 1.2 × 1024 
E) 60

Question 4

A 1.36-g sample of magnesium nitrate, Mg(NO3)2, contains ________ mol of this compound.

Accepted Answer

A) 2.32 
B) 1.65 
C) 0.111 
D) 0.0182 
E) 0.00917 
A) 2.32 
B) 1.65 
C) 0.111 
D) 0.0182 
E) 0.00917

Question 5

Calcium oxide reacts with water in a combination reaction to produce calcium hydroxide: CaO (s) + H2O (l) → Ca(OH)2 (s)
In a particular experiment, a 2.00-g sample of CaO is reacted with excess water and 2.14 g of Ca(OH)2 is recovered. What is the percent yield in this experiment?

Accepted Answer

A) 107 
B) 1.07 
C) 2.88 
D) 81.1 
E) 93.3 
A) 107 
B) 1.07 
C) 2.88 
D) 81.1 
E) 93.3

Question 6

Lead (II)carbonate decomposes to give lead (II)oxide and carbon dioxide: PbCO3 (s) → PbO (s) + CO2 (g)
________ grams of lead (II)oxide will be produced by the decomposition of 8.75 g of lead (II)carbonate?

Accepted Answer

A) 0.41 
B) 2.50 
C) 0.00936 
D) 7.31 
E) 11.7 
A) 0.41 
B) 2.50 
C) 0.00936 
D) 7.31 
E) 11.7

Question 7

Under appropriate conditions, nitrogen and hydrogen undergo a combination reaction to yield ammonia: N2 (g) + 3H2 (g) → 2NH3 (g)
If the reaction yield is 87.5%, how many moles of N2 are needed to produce 3.00 mol of NH3?

Accepted Answer

A) 0.166 
B) 1.00 
C) 1.5 
D) 1.71 
E) 2.32 
A) 0.166 
B) 1.00 
C) 1.5 
D) 1.71 
E) 2.32

Question 8

Which one of the following is not true concerning automotive air bags?

Accepted Answer

A) They are inflated as a result of a decomposition reaction. 
B) They are loaded with sodium azide initially. 
C) The gas used for inflating them is oxygen. 
D) The two products of the decomposition reaction are sodium and nitrogen. 
E) A gas is produced when the air bag activates. 
A) They are inflated as a result of a decomposition reaction. 
B) They are loaded with sodium azide initially. 
C) The gas used for inflating them is oxygen. 
D) The two products of the decomposition reaction are sodium and nitrogen. 
E) A gas is produced when the air bag activates.

Question 9

A sample of C3H8O that contains 200 molecules contains ________ carbon atoms.

Accepted Answer

A) 600 
B) 200 
C) 3.61 × 1026 
D) 1.20 × 1026 
E) 4.01 × 1025 
A) 600 
B) 200 
C) 3.61 × 1026 
D) 1.20 × 1026 
E) 4.01 × 1025

Question 10

Calcium oxide reacts with water in a combination reaction to produce calcium hydroxide: CaO (s) + H2O (l) → Ca(OH)2 (s)
A 3.50-g sample of CaO is reacted with 3.38 g of H2O. How many grams of water remain after completion of reaction?

Accepted Answer

A) 0.00 
B) 0.00694 
C) 2.25 
D) 1.04 
E) 0.125 
A) 0.00 
B) 0.00694 
C) 2.25 
D) 1.04 
E) 0.125

Question 11

Calculate the percentage by mass of lead in Pb(NO3)2.

Accepted Answer

A) 38.6 
B) 44.5 
C) 62.6 
D) 65.3 
E) 71.2 
A) 38.6 
B) 44.5 
C) 62.6 
D) 65.3 
E) 71.2

Question 12

Sulfur and fluorine react in a combination reaction to produce sulfur hexafluoride: S (s) + 3F2 (g) → SF6 (g)
In a particular experiment, the percent yield is 79.0%. This means that in this experiment, a 7.90-g sample of fluorine yields ________ g of SF6.

Accepted Answer

A) 30.3 
B) 10.1 
C) 7.99 
D) 24.0 
E) 0.110 
A) 30.3 
B) 10.1 
C) 7.99 
D) 24.0 
E) 0.110

Question 13

How many moles of sodium carbonate contain 1.773 × 1017 carbon atoms?

Accepted Answer

A) 5.890 × 10-7 
B) 2.945 × 10-7 
C) 1.473 × 10-7 
D) 8.836 × 10-7 
E) 9.817 × 10-8 
A) 5.890 × 10-7 
B) 2.945 × 10-7 
C) 1.473 × 10-7 
D) 8.836 × 10-7 
E) 9.817 × 10-8

Question 14

When the following equation is balanced, the coefficients are ________. C8H18 + O2 → CO2 + H2O

Accepted Answer

A) 4, 50, 16, 18 
B) 1, 5, 2, 2 
C) 2, 2, 7, 1 
D) 1, 13, 8, 9 
E) 2, 25, 16, 18 
A) 4, 50, 16, 18 
B) 1, 5, 2, 2 
C) 2, 2, 7, 1 
D) 1, 13, 8, 9 
E) 2, 25, 16, 18

Question 15

How many moles of lithium phosphate (Li3PO4)are contained in 66.6 g of lithium phosphate?

Accepted Answer

A) 0.575 
B) 7710 
C) 1.11 × 10-22 
D) 4.01 × 1025 
E) 116 
A) 0.575 
B) 7710 
C) 1.11 × 10-22 
D) 4.01 × 1025 
E) 116

Question 16

If the reaction yield is 94.4%, what mass in grams of hydrogen is produced by the reaction of 4.73 g of magnesium with 1.83 g of water? Mg (s) + 2H2O (l) → Mg(OH)2 (s) + H2 (g)

Accepted Answer

A) 0.0962 
B) 0.0162 
C) 0.0485 
D) 0.219 
E) 0.204 
A) 0.0962 
B) 0.0162 
C) 0.0485 
D) 0.219 
E) 0.204

Question 17

Solid aluminum and gaseous oxygen react in a combination reaction to produce aluminum oxide: 4Al (s) + 3O2 (g) → 2Al2O3 (s)
In a particular experiment, the reaction of 2.5 g of Al with 2.5 g of O2 produced 3.5 g of Al2O3. The % yield of the reaction is ________.

Accepted Answer

A) 74 
B) 37 
C) 47 
D) 66 
E) 26 
A) 74 
B) 37 
C) 47 
D) 66 
E) 26

Question 18

Water can be formed from the stoichiometric reaction of hydrogen with oxygen:
2H2 (g) + O2 (g) → 2H2O (g)
A complete reaction of 5.0 g of O2 with excess hydrogen produces ________ g of H2O.

Accepted Answer

Question 19

The combustion of carbon disulfide in the presence of excess oxygen yields carbon dioxide and sulfur dioxide:
CS2 (g) + 3O2 (g) → CO2 (g) + 2SO2 (g)
The combustion of 15 g of CS2 in the presence of excess oxygen yields ________ g of SO2.

Accepted Answer

Question 20

Sulfur and oxygen react to produce sulfur trioxide. In a particular experiment, 7.9 grams of SO3 are produced by the reaction of 6.0 grams of O2 with 7.0 grams of S. What is the % yield of SO3 in this experiment? S (s) + O2 (g) → SO3 (g) (not balanced)

Accepted Answer

A) 48 
B) 62 
C) 73 
D) 79 
E) 92 
A) 48 
B) 62 
C) 73 
D) 79 
E) 92

Exam 3: Stoichiometry: Calculations With Chemical Formulas and Equations

What is the mass in grams of 9.76 × 1012 atoms of naturally occurring potassium?

A compound contains 40.0% C, 6.71% H, and 53.29% O by mass. The molecular weight of the compound is 60.05 amu. The molecular formula of this compound is ________.

There are ________ oxygen atoms in 30 molecules of C20H42S3O2.

A 1.36-g sample of magnesium nitrate, Mg(NO3)2, contains ________ mol of this compound.

Calcium oxide reacts with water in a combination reaction to produce calcium hydroxide: CaO (s) + H2O (l) → Ca(OH)2 (s) In a particular experiment, a 2.00-g sample of CaO is reacted with excess water and 2.14 g of Ca(OH)2 is recovered. What is the percent yield in this experiment?

Lead (II)carbonate decomposes to give lead (II)oxide and carbon dioxide: PbCO3 (s) → PbO (s) + CO2 (g) ________ grams of lead (II)oxide will be produced by the decomposition of 8.75 g of lead (II)carbonate?

Under appropriate conditions, nitrogen and hydrogen undergo a combination reaction to yield ammonia: N2 (g) + 3H2 (g) → 2NH3 (g) If the reaction yield is 87.5%, how many moles of N2 are needed to produce 3.00 mol of NH3?

Which one of the following is not true concerning automotive air bags?

A sample of C3H8O that contains 200 molecules contains ________ carbon atoms.

Calcium oxide reacts with water in a combination reaction to produce calcium hydroxide: CaO (s) + H2O (l) → Ca(OH)2 (s) A 3.50-g sample of CaO is reacted with 3.38 g of H2O. How many grams of water remain after completion of reaction?

Calculate the percentage by mass of lead in Pb(NO3)2.

Sulfur and fluorine react in a combination reaction to produce sulfur hexafluoride: S (s) + 3F2 (g) → SF6 (g) In a particular experiment, the percent yield is 79.0%. This means that in this experiment, a 7.90-g sample of fluorine yields ________ g of SF6.

How many moles of sodium carbonate contain 1.773 × 1017 carbon atoms?

When the following equation is balanced, the coefficients are ________. C8H18 + O2 → CO2 + H2O

How many moles of lithium phosphate (Li3PO4)are contained in 66.6 g of lithium phosphate?

If the reaction yield is 94.4%, what mass in grams of hydrogen is produced by the reaction of 4.73 g of magnesium with 1.83 g of water? Mg (s) + 2H2O (l) → Mg(OH)2 (s) + H2 (g)

Solid aluminum and gaseous oxygen react in a combination reaction to produce aluminum oxide: 4Al (s) + 3O2 (g) → 2Al2O3 (s) In a particular experiment, the reaction of 2.5 g of Al with 2.5 g of O2 produced 3.5 g of Al2O3. The % yield of the reaction is ________.

Water can be formed from the stoichiometric reaction of hydrogen with oxygen: 2H2 (g) + O2 (g) → 2H2O (g) A complete reaction of 5.0 g of O2 with excess hydrogen produces ________ g of H2O.

The combustion of carbon disulfide in the presence of excess oxygen yields carbon dioxide and sulfur dioxide: CS2 (g) + 3O2 (g) → CO2 (g) + 2SO2 (g) The combustion of 15 g of CS2 in the presence of excess oxygen yields ________ g of SO2.

Sulfur and oxygen react to produce sulfur trioxide. In a particular experiment, 7.9 grams of SO3 are produced by the reaction of 6.0 grams of O2 with 7.0 grams of S. What is the % yield of SO3 in this experiment? S (s) + O2 (g) → SO3 (g) (not balanced)

Introduction: Matter and Measurement

Atoms, Molecules, and Ions

Aqueous Reactions and Solution Stoichiometry

Thermochemistry

Electronic Structure of Atoms

Periodic Properties of the Elements

Basic Concepts of Chemical Bonding

Molecular Geometry and Bonding Theories

Gases

Liquids and Intermolecular Forces

Solids and Modern Materials

Properties of Solutions

Chemical Kinetics

Chemical Equilibrium

Acid-Base Equilibria

Additional Aspects of Aqueous Equilibria

Chemistry of the Environment

Chemical Thermodynamics

Electrochemistry

Nuclear Chemistry

Chemistry of the Nonmetals

Transition Metals and Coordination Chemistry

The Chemistry of Life: Organic and Biological Chemistry

Filters

What is the mass in grams of 9.76 × 10¹² atoms of naturally occurring potassium?

There are ________ oxygen atoms in 30 molecules of C₂₀H₄₂S₃O₂.

A 1.36-g sample of magnesium nitrate, Mg(NO₃)₂, contains ________ mol of this compound.

Calcium oxide reacts with water in a combination reaction to produce calcium hydroxide: CaO (s) + H₂O (l) → Ca(OH)₂ (s) In a particular experiment, a 2.00-g sample of CaO is reacted with excess water and 2.14 g of Ca(OH)₂ is recovered. What is the percent yield in this experiment?

Lead (II)carbonate decomposes to give lead (II)oxide and carbon dioxide: PbCO₃ (s) → PbO (s) + CO₂ (g) ________ grams of lead (II)oxide will be produced by the decomposition of 8.75 g of lead (II)carbonate?

Under appropriate conditions, nitrogen and hydrogen undergo a combination reaction to yield ammonia: N₂ (g) + 3H₂ (g) → 2NH₃ (g) If the reaction yield is 87.5%, how many moles of N₂ are needed to produce 3.00 mol of NH₃?

A sample of C₃H₈O that contains 200 molecules contains ________ carbon atoms.

Calcium oxide reacts with water in a combination reaction to produce calcium hydroxide: CaO (s) + H₂O (l) → Ca(OH)₂ (s) A 3.50-g sample of CaO is reacted with 3.38 g of H₂O. How many grams of water remain after completion of reaction?

Calculate the percentage by mass of lead in Pb(NO₃)₂.

Sulfur and fluorine react in a combination reaction to produce sulfur hexafluoride: S (s) + 3F₂ (g) → SF₆ (g) In a particular experiment, the percent yield is 79.0%. This means that in this experiment, a 7.90-g sample of fluorine yields ________ g of SF₆.

How many moles of sodium carbonate contain 1.773 × 10¹⁷ carbon atoms?

When the following equation is balanced, the coefficients are ________. C₈H₁₈ + O₂ → CO₂ + H₂O

How many moles of lithium phosphate (Li₃PO₄)are contained in 66.6 g of lithium phosphate?

If the reaction yield is 94.4%, what mass in grams of hydrogen is produced by the reaction of 4.73 g of magnesium with 1.83 g of water? Mg (s) + 2H₂O (l) → Mg(OH)₂ (s) + H₂ (g)

Solid aluminum and gaseous oxygen react in a combination reaction to produce aluminum oxide: 4Al (s) + 3O₂ (g) → 2Al₂O₃ (s) In a particular experiment, the reaction of 2.5 g of Al with 2.5 g of O₂ produced 3.5 g of Al₂O₃. The % yield of the reaction is ________.

Water can be formed from the stoichiometric reaction of hydrogen with oxygen: 2H₂ (g) + O₂ (g) → 2H₂O (g) A complete reaction of 5.0 g of O₂ with excess hydrogen produces ________ g of H₂O.

The combustion of carbon disulfide in the presence of excess oxygen yields carbon dioxide and sulfur dioxide: CS₂ (g) + 3O₂ (g) → CO₂ (g) + 2SO₂ (g) The combustion of 15 g of CS₂ in the presence of excess oxygen yields ________ g of SO₂.

Sulfur and oxygen react to produce sulfur trioxide. In a particular experiment, 7.9 grams of SO₃ are produced by the reaction of 6.0 grams of O₂ with 7.0 grams of S. What is the % yield of SO₃ in this experiment? S (s) + O₂ (g) → SO₃ (g) (not balanced)