Stoichiometry
Devon Bateman
Essential Question
• Why is a foot…a foot?
–King Henry I had a
foot 12 inches long.
Unit Questions
• What are measurements?
• What do we measure?
• How do we measure?
• Why do we measure?
• How do chemists
measure molecules?
Overview
• Measurement
– List examples of measurement
– Define purpose of measurement
– Explain chemist’s use of the mole
• Stoichiometry
– Relate stoichiometry to a recipe
– Demonstrate mole ratios in balanced
equations
WHAT DO WE MEASURE
AND HOW?
• Measurements allow us
compare or analyze data.
• Therefore, measurements
must be reasonable.
• How do chemists count
molecules?
• Can chemists count by
measuring?
Chemists count using the mole.
• Mole: the unit used to
measure the amount of a
substance
• 1 mole = 6.02x1023 particles
• Stoichiometry- the study of
mole and mass relationships
in a chemical reaction
http://www.lsua.us/chem1001/stoichiometry/stoichiometry.html
• The mass of the reactants
must equal the mass of the
products.
H2
+
Cl2  2 HCl
• A balanced chemical
equation is very
similar to a recipe.
• Coefficients represent the
mole ratio between
substances.
6 O2 + C6H12O6  6 CO2 + 6 H2O
Example
4 Fe + 3 O2  2 Fe2O3
• It takes 4 moles iron &
3 moles oxygen to produce
2 moles iron (III) oxide.
Conclusion
• The mole allows chemists to
analyze chemical reactions.
• Balanced equations can be
treated like recipes.
• Amount of ingredients determines
the amount of product