Chemistry Notes
Chapter 9 - Stoichiometry
Section 9.1 - 9.3 - Stoichiometry Using Chemical Equations to Calculate Moles, Mass, Limiting Reactant and Percent Yield
Mole = Avogadro's Number of particles of a substance
= unit equivalent to 6.02 x 1023 atoms or molecules
= unit equivalent to 12.0 grams of Carbon-12 (molar-mass from the
periodic table)
Mole ratio = whole-number ratio of moles of substances undergoing reaction
found from the coefficients from a balanced equation
Molar mass = mass of one mole of a pure substance; the given atomic mass unit, mass number,
or gram formula weight from the periodic table
Stoichiometry = using a known ratio of moles to calculate an unknown quantity of mass or
moles in a chemical reaction
3 steps to convert mass to mass in stoichiometry
1. convert given mass to moles by dividing by the molar mass
2. find mole ratio between unknown and given moles
3. convert unknown moles to mass by multiplying by molar mass
Limiting reactant = the reactant that is completely consumed in a chemical reaction; the limiting
reactant determines the maximum amount of product
Excess reactant = the reactant that is not completely consumed and has left over amounts in a
chemical reaction; the excess reactant does not determine the product
Actual yield (experimental yield) = the amount produced in the chemical reaction and is
measured in the experiment (the given amount)
Theoretical yield = the maximum amount of product that is produced from the limiting reactant
if there is no percent error or loss of product
Percent yield = [Actual yield/Theoretical yield] x 100%
Percent error = /100% - Percent yield/
Mrs. Drurey
- 1 of 3 -
Newton South High School
Chemistry Notes
Chapter 9 - Stoichiometry
Mole Conversion Chart
miznerscience.org
Mrs. Drurey
- 2 of 3 -
Newton South High School
Chemistry Notes
Chapter 9 - Stoichiometry
Stoichiometry: Converting from Known Mass to Unknown Mass
MASS
A
MOLE
A
MOLE
B
MASS
B
Step 1: Convert Mass A to Moles A
- divide by the molar mass of A to find moles A
Step 2: Convert Moles A to Moles B
- multiply by the mole ratio from the coefficients from the balanced
equation
Mole ratio:
given moles x (moles looking for)
(moles to cancel out)
Step 3: Convert Moles B to Mass B
- multiply by the molar mass of B to find mass of B
Mrs. Drurey
- 3 of 3 -
Newton South High School