What is
Stoichiometry?
Objectives:
6.0 Solve stoichiometric problems involving relationships among the
number of particles, moles, and masses of reactants and products in
a chemical reaction
6.3 Identifying the nomenclature of ionic compounds, binary
compounds, and acids
6.4 Classifying chemical reactions as composition, decomposition,
single replacement, or double replacement
Other AOD C.6.1 Define stoichiometry, reactants, and products.
Other AOD C.6.2 Explain the law of conservation of mass.
Other AOD C.6.3 Explain the concept of mole in terms of Avogadro's
number.
Stoichiometry
• Def.: the quantitative study of
relationships between amounts of
reactants used and products formed in a
chemical reaction
• Let’s think for a moment. If I hand you a
dozen chocolate chips, can you make a
dozen chocolate chip cookies?
• Well, every chemical equation is just a
recipe!
Let’s Review!
• Iron + oxygen react to produce iron (III)
oxide.
1. Write AND BALANCE the chemical
equation.
ANSWER: 4 Fe(s) + 3O2(g)→ 2Fe2O3(s)
2. What type of reaction is this?
3. How many moles of each compound are
represented?
4. How many grams of each compound are
represented?
Review, continued…..
• Aluminum + bromine react to produce
aluminum bromide
1. Write AND BALANCE the chemical
equation.
ANSWER: 2Al(s) + 3Br2(l)→ 2AlBr3(s)
2. What type of reaction is this?
3. How many moles of each compound are
represented?
4. How many grams of each compound are
represented?
Review – 1 More!
• Propane (C3H8) and oxygen react to
produce carbon dioxide and water.
1. Write AND BALANCE the chemical
equation.
ANSWER: C3H8(g) + 5O2(g)→ 3CO2(g) + 4H2O
2. What type of reaction is this?
3. How many moles of each compound are
represented?
4. How many grams of each compound are
represented?
Law of Conservation of Mass
• In every example, mass was conserved,
meaning the mass of the reactants
EQUALS the mass of the products!
• While mass was equal on both sides of
the equations, what was different?
ANSWER: number of molecules or number
of moles
Assignment
• Let’s look at Example Problem 12-1 on
p.355. (This is the last equation we
balanced.)
• Notice how they write the equation “in
terms of” molecules, moles, and mass.
• Now do the Practice Problems on p.356 --- ONLY demonstrating conservation of
mass, not the rest of the directions.
Mole Ratios
• Def.: the ratio of the number of moles of
any two substances in a balanced
chemical equation.
• Let’s look back at the 3 equations we
balanced.
• In the first one, we can identify several
mole ratios:
– 4Fe/3O2
– 4Fe/2Fe2O3
– 3O2/2Fe2O3
OR
OR
OR
3O2/4Fe
2Fe2O3/4Fe
2Fe2O3/3O2
Mole Ratios, continued…..
•
•
What are the possible mole ratios for the
other two example problems we
worked?
Assignment:
1. Practice Problems (p.357)
2. Study Guide for Content Mastery: pp.67-68