Stoichiometry

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This is a 7 point assignment

Objectives: After completing this unit, students should be able to:

1. Write a balanced chemical equation given a word description or the formulas of the reactants and products.
2. Identify a chemical reaction as combination, decomposition or combustion. (See the Chemical Reaction Handout.)
3. Given the reactants and the reaction type (combination, decomposition or combustion), predict the products and then balance the equation. (See the Chemical Reaction Handout)
4. Given a chemical formula or name, convert among moles, grams, amu, molecules and atoms.
5. Given the name or formula of an element or compound, determine its molar mass.
6. Given the chemical formula or name of a substance, calculate its percent composition.
7. Determine the empirical formula of a compound from a molecular formula or percent composition.
8. Given the empirical formula and molar mass of a compound determine its molecular formula.
9. Calculate the mass of a particular substance produced or used in a chemical equation.
10. Given the amounts of two or more reactants and the chemical equation, determine the limiting reagent and the theoretical yield of the product.
11. Given the theoretical yield and the actual yield, calculate the percent yield.

Reading and Homework Exercises

Table of Contents from:   Chemistry 2e: Chapter 3 (sections 3.1 and 3.2), Chapter 4 (Selected sections, see specific reading recommendations for each link)

Ch 3 Introduction

3.1 Formula Mass and the Mole Concept

Section 3.1 Practice – For the problems in this section, do the following in your calculations:

1. Use atomic mass values from the periodic table rounded to one decimal place.  For example, carbon = 12.0 g/mol or amu/atom, boron = 10.8.
2. report answers to the proper number of significant figures unless otherwise instructed.
3. If you use scientific notation, use the following format: for 5.67 X 10²² type
4. 5.67E22, for 5.67 X 10^-4 type 5.67E-4.

Question 1:

Question 2:

Question 3: Answer the following for calcium phosphate, Ca₃(PO₄)₂:

3.2 Determining Empirical and Molecular Formulas

Questions 4-6 give you practice determining percent composition from chemical formula

Question 4: Determine the percent composition of each element in PF₅

Question 5: Determine the percent composition of each element in CH₄O

Question 6: Determine the percent composition of each element in Mg(C₂H₃O₂)₂

Questions 7-9 allow you to check your understanding of empirical and molecular formulas

Question 7:

Question 8:

Question 9:

Ch 4 Introduction

4.1 Writing and Balancing Chemical Equations

To help with these problems, do the following background reading first:

Read the following parts of this Section 4.1 in OpenStax:

1. • Initial part
   • “Balancing Equations” subsection
   • “Additional Information in Chemical Equations” subsection
   • Omit reading of this subsection “Equations for ionic reactions” (which will be covered later in the course)

Read the following sections in the CHEM 151 Reaction Handout in the Content area of your course’s D2L site:

• Introduction
• Balancing Chemical Equations
• Types of Chemical Reactions:
  • Combination Reactions
  • Decomposition Reactions
  • Combustion reactions

Questions 10-15 allow you to practice balancing and classifying reactions

Answer Questions 10 and 11 for the following reaction:

A Al₂O₃ → B Al + C O₂

Question 10:

Question 11:

Answer Questions 12 and 13 for the following reaction:

A K₂O + B H₂O → C KOH

Question 12:

Question 13:

Answer Questions 14 and 15 for the following reaction:

A C₄H₉OH + B O₂   → C CO₂ + D H₂O

Question 14:

Question 15:

Questions 16-19 allow to practice predicting products of reactions, then balancing them

For the next 4 questions, complete and balance the reactions that would occur given the reactants and reaction type, and identify the correct products and their coefficients.

Question 16:

Question 17:

Question 18:

Question 19:

4.3 Reaction Stoichiometry

Questions 20-23 allow you to practice reaction stoichiometry problems

Question 20:

Question 21:

Question 22: Answer the following question for the reaction

4 CuO + CH₄ —-> 2 H₂O + 4 Cu + CO₂

Question 23: Answer the following questions for the reaction

N₂ + 3 H₂ —-> 2 NH₃

4.4 Reaction Yields

Questions 24-25 check your understanding of the concept of limiting reactant (limiting reagent) in chemical reactions and limiting reactant stoichiometry problems

Question 24:

Question 25:

Questions 26-29 add the concepts of actual, theoretical, and percent yield to limiting reactant stoichiometry problems

Answer questions 26 and 27 for the reaction

2 S(s) + 3 O₂(g) —-> 2 SO₃(g)

Question 26:

Question 27:

Answer questions 28 and 29 for the reaction

C₂H₄ + 3 O₂ —-> 2 CO₂ + 2 H₂O

Question 28:

Question 29: