Lesson Plans

Chemistry: The Central Science 9th Edition ©2003

by Brown, LeMay, and Bursten

Weeks 3–4: Stoichiometry

Chapter 3: Stoichiometry: Calculations With Chemical Formulas and Equations; Sections: 3.3–3.7
Chapter 4: Aqueous Reactions and Solution Stoichiometry; Sections: 4.5–4.6

This section presents the fundamental quantitative skills students will need for the rest of the course.

College Board Performance Objectives:

• Calculate the atomic weight (average atomic mass) of an element from the relative abundances and masses of its naturally occurring isotopes.
• Calculate the percentage composition of a compound from its formula.
• Calculate the molar mass of a substance from its chemical formula.
• Be able to interconvert between moles, mass, and number of particles of a substance.
• Calculate the empirical formula of a compound from either elemental percent composition or quantity of CO₂ and H₂O produced from its combustion.
• Calculate the molecular formula of a compound from the empirical formula and molecular weight.
• Find the mass of any substance in a chemical reaction from the mass of one substance.
• Determine the limiting reactant (limiting reagent) in a reaction and then calculate the amount of each product and the mass of the excess reactant left over.
• Calculate theoretical yield.
• Calculate moles of solute, volume of solution, or molarity of the solution from the other two.
• Recognize and solve dilution problems.
• Calculate the volume of a certain molarity solution required to react with another solution of known molarity.
• Calculate the mass of a substance that would be required to react with a given volume of a solution of known molarity.
• Calculate mass of solute or concentration of an unknown solution from titration data.

College Board Lab Objectives:

• To become familiar with chemical formulas (empirical and molecular) and how they are obtained experimentally.
• Learn some basic lab procedures, the chemistry of copper, and the concept of percent yield.

Suggested Labs:

• Experiment 5, Chemical Formulas, p. 47
• Experiment 6, Chemical Reactions of Copper and Percent Yield, p. 59

Resources:

• Instructor's Resource Manual, pp. 32–39 and pp. 49–54
• Student's Guide, pp. 37–53 and pp. 68–79
• Test Bank, p. 102–130, and pp. 150–168
• Instructor's Resource CD, Chapters 3 and 4

Pacing Guide:

• Atomic and Molecular Mass and the Mole—1 day
• Percent Composition, Formulas, and Combustion Analysis—3 days
• Reaction Stoichiometry—3 days
• Limiting Reactants—1 day
• Solution Concentration; M—2 days
• Solution Stoichiometry (Titration)—1 day
• Block Scheduling
  Atomic and Molecular Mass and the Mole; and Percent Composition, Formulas and Combustion Analysis can be completed together. Reaction Stoichiometry and Limiting Reactants will require at least two blocks, as will Solution Concentration and Solution Stoichiometry. It is extremely important that students do all suggested exercises!

Key Words:

Suggested Exercises:
Critical thinking questions and end-of-chapter activities are included in these exercises.

• pp. 105–111, # 15, 17, 19, 21, 27, 29, 31, 33, 35, 37, 39, 41, 43, 45, 47, 49, 51, 53, 55, 57, 59, 61, 63, 65, 69, 71, 73, 75, 77, 79, 85, 87, 90, 95, 103.
• eMedia Exercises: p. 111, # 106.
• pp. 147–150, # 49, 51, 53, 55, 57, 59, 61, 63, 65, 67, 69, 71, 73, 75, 86, 89, 93, 99, 102.
• eMedia Exercises: p. 151 # 109.

Troubleshooting Tips/Error Traps:

• Stress that the average mass of an atom is in amu and that the mass of a mole (Avogadro's number) of these atoms is the same number of grams.
• Electrons have negligible mass, therefore ions have essentially the same mass as their atoms.
• Reaction stoichiometry requires a correct, balanced chemical equation.