CHEM 120
EXAM 2 — CHAPTERS 5–8
Enhanced Questions & Answers • Exam-Focused Practice Guide
Original study resource designed around the publicly visible themes associated with CHEM
120 Exam 2 materials. It is not an official Chamberlain College of Nursing examination and is not
a reproduction of any paid or locked study document.
What is inside
• 100+ original exam-style questions and answers
• Chemical equations, mole concepts, stoichiometry and solution calculations
• Acids, bases, neutralization and oxidation–reduction concepts
• Gas-law reasoning and quantitative problem solving
• Worked calculations, memory aids, common traps and application questions
• Rapid-review section and mixed practice exam
Best use: Attempt each question before reading the answer. Mark questions you miss, then revisit the corresponding
concept box and redo the calculation without looking.
CHEM 120 • Original Enhanced Exam 2 Study Guide Page 1
,CONTENTS
1. Chapter 5 — Chemical Reactions & Equations
2. Chapter 6 — The Mole, Molar Mass & Stoichiometry
3. Chapter 7 — Solutions, Acids & Bases
4. Chapter 8 — Gases, Redox & Integrated Calculations
5. High-Yield Formula & Memory Sheet
6. Mixed Exam Practice — 30 Questions
7. Answer Key & Final Exam Traps
Important: The chapter labels below are organized to match the subject area and title of the supplied Stuvia listing, while
the questions and explanations are newly written. Exact chapter sequencing can vary by textbook edition.
CHEM 120 • Original Enhanced Exam 2 Study Guide Page 2
, CHAPTER 5 — CHEMICAL REACTIONS & EQUATIONS
Core idea: A chemical equation is a compact model of a chemical change. Reactants appear on the left, products on the
right, and coefficients communicate the relative amounts involved. The equation must obey conservation of atoms.
Quick Review
• Reactants → substances consumed; products → substances formed.
• Coefficients balance an equation; subscripts belong to chemical formulas and should not be changed when
balancing.
• State symbols: (s) solid, (l) liquid, (g) gas, (aq) aqueous.
• A balanced equation gives mole ratios used in stoichiometric calculations.
• Mass is conserved even though atoms are rearranged.
1. Question: Which information is normally communicated by a chemical equation?
Answer: It identifies reactants and products and can indicate physical states when state symbols are included. A
balanced equation also gives the relative mole ratios between substances.
Exam trap: Do not confuse coefficients with grams. A coefficient in a balanced equation represents relative amounts in
moles, particles, or—in appropriate gas contexts—volume ratios.
2. Question: Why must chemical equations be balanced?
Answer: Because atoms are not created or destroyed in an ordinary chemical reaction. The number of atoms of each
element must be the same on both sides of the equation.
3. Question: What does the equation 2H■ + O■ → 2H■O tell you?
Answer: It gives a 2:1:2 mole ratio: 2 mol H■ react with 1 mol O■ to produce 2 mol H■O. At the molecular level, 2
molecules of H■ react with 1 molecule of O■ to produce 2 molecules of H■O.
Exam trap: The coefficients do not mean 2 g H■ + 1 g O■. Grams must be calculated using molar masses.
4. Question: What is the difference between a coefficient and a subscript?
Answer: A coefficient multiplies the entire chemical formula and can be changed to balance an equation. A subscript
is part of the formula and indicates the number of atoms of an element in one particle; changing it changes the identity
of the substance.
5. Question: Balance: H■ + O■ → H■O.
Answer: 2H■ + O■ → 2H■O. Count oxygen first, then hydrogen, and use the smallest whole-number coefficients.
6. Question: Balance: Fe + O■ → Fe■O■.
Answer: 4Fe + 3O■ → 2Fe■O■. Four Fe atoms and six O atoms appear on each side.
7. Question: Balance: Al + HCl → AlCl■ + H■.
Answer: 2Al + 6HCl → 2AlCl■ + 3H■.
8. Question: What does (aq) mean?
Answer: The substance is dissolved in water, forming an aqueous solution. It does not simply mean 'liquid'; the
solvent is specifically water.
Exam trap: Aqueous and liquid are not interchangeable. Water itself is (l), while a dissolved ionic compound may be (aq).
9. Question: What is a synthesis reaction?
CHEM 120 • Original Enhanced Exam 2 Study Guide Page 3
EXAM 2 — CHAPTERS 5–8
Enhanced Questions & Answers • Exam-Focused Practice Guide
Original study resource designed around the publicly visible themes associated with CHEM
120 Exam 2 materials. It is not an official Chamberlain College of Nursing examination and is not
a reproduction of any paid or locked study document.
What is inside
• 100+ original exam-style questions and answers
• Chemical equations, mole concepts, stoichiometry and solution calculations
• Acids, bases, neutralization and oxidation–reduction concepts
• Gas-law reasoning and quantitative problem solving
• Worked calculations, memory aids, common traps and application questions
• Rapid-review section and mixed practice exam
Best use: Attempt each question before reading the answer. Mark questions you miss, then revisit the corresponding
concept box and redo the calculation without looking.
CHEM 120 • Original Enhanced Exam 2 Study Guide Page 1
,CONTENTS
1. Chapter 5 — Chemical Reactions & Equations
2. Chapter 6 — The Mole, Molar Mass & Stoichiometry
3. Chapter 7 — Solutions, Acids & Bases
4. Chapter 8 — Gases, Redox & Integrated Calculations
5. High-Yield Formula & Memory Sheet
6. Mixed Exam Practice — 30 Questions
7. Answer Key & Final Exam Traps
Important: The chapter labels below are organized to match the subject area and title of the supplied Stuvia listing, while
the questions and explanations are newly written. Exact chapter sequencing can vary by textbook edition.
CHEM 120 • Original Enhanced Exam 2 Study Guide Page 2
, CHAPTER 5 — CHEMICAL REACTIONS & EQUATIONS
Core idea: A chemical equation is a compact model of a chemical change. Reactants appear on the left, products on the
right, and coefficients communicate the relative amounts involved. The equation must obey conservation of atoms.
Quick Review
• Reactants → substances consumed; products → substances formed.
• Coefficients balance an equation; subscripts belong to chemical formulas and should not be changed when
balancing.
• State symbols: (s) solid, (l) liquid, (g) gas, (aq) aqueous.
• A balanced equation gives mole ratios used in stoichiometric calculations.
• Mass is conserved even though atoms are rearranged.
1. Question: Which information is normally communicated by a chemical equation?
Answer: It identifies reactants and products and can indicate physical states when state symbols are included. A
balanced equation also gives the relative mole ratios between substances.
Exam trap: Do not confuse coefficients with grams. A coefficient in a balanced equation represents relative amounts in
moles, particles, or—in appropriate gas contexts—volume ratios.
2. Question: Why must chemical equations be balanced?
Answer: Because atoms are not created or destroyed in an ordinary chemical reaction. The number of atoms of each
element must be the same on both sides of the equation.
3. Question: What does the equation 2H■ + O■ → 2H■O tell you?
Answer: It gives a 2:1:2 mole ratio: 2 mol H■ react with 1 mol O■ to produce 2 mol H■O. At the molecular level, 2
molecules of H■ react with 1 molecule of O■ to produce 2 molecules of H■O.
Exam trap: The coefficients do not mean 2 g H■ + 1 g O■. Grams must be calculated using molar masses.
4. Question: What is the difference between a coefficient and a subscript?
Answer: A coefficient multiplies the entire chemical formula and can be changed to balance an equation. A subscript
is part of the formula and indicates the number of atoms of an element in one particle; changing it changes the identity
of the substance.
5. Question: Balance: H■ + O■ → H■O.
Answer: 2H■ + O■ → 2H■O. Count oxygen first, then hydrogen, and use the smallest whole-number coefficients.
6. Question: Balance: Fe + O■ → Fe■O■.
Answer: 4Fe + 3O■ → 2Fe■O■. Four Fe atoms and six O atoms appear on each side.
7. Question: Balance: Al + HCl → AlCl■ + H■.
Answer: 2Al + 6HCl → 2AlCl■ + 3H■.
8. Question: What does (aq) mean?
Answer: The substance is dissolved in water, forming an aqueous solution. It does not simply mean 'liquid'; the
solvent is specifically water.
Exam trap: Aqueous and liquid are not interchangeable. Water itself is (l), while a dissolved ionic compound may be (aq).
9. Question: What is a synthesis reaction?
CHEM 120 • Original Enhanced Exam 2 Study Guide Page 3
