1. Stoichiometry
Coach Cox

2. What is Stoichiometry?
Stoichiometry is the study of the quantitative relationships between the amounts of reactants used and the products formed by a chemical reaction
Stoichiometry is based on the Law of Conservation of Mass
Mass of Reactants = Mass of Products

3. What is stoichiometry used for?
Stoichiometry is used to tell chemists:
How much product will be produced
How much reactant is needed to make a product

4. Stoichiometry and the Balanced Equation
Coefficients in a balanced chemical equation can tell us:
The # of individual particles: (atoms, molecules, or FUN)
The # of moles
The mass of reactants and products (Found using the molar mass (MM) of the compounds)

5. Example
Balance the Following Equation: ___ Fe(s) + ___ O2(g) ___ Fe2O3(s)

6. Example Answer
Balance the Following Equation: 4 Fe(s) + 3 O2(g)  2 Fe2O3(s)

7. Fill in the Table Fill in the table below: Reactants Products
Name: Iron
Oxygen Gas 
Iron (III) Oxide
Formula: Fe
O 
Fe2O3
_____atoms of Fe
_____ molecules O 
_____ formula units Fe2O3
_____ moles Fe
_____ moles O 
_____ moles Fe2O3
_____ grams Fe
_____ grams O 
_____ grams Fe2O3
____ grams reactants 
_____ grams products
Name: Iron
Oxygen 
Iron (III) Oxide
Formula: Fe
O 
Fe2O3
___4__atoms of Fe
__3___ molecules O 
___2__ formula units Fe2O
__4___ moles Fe
___3__ moles O 
__2___ moles Fe2O3
(55.845x4) _223.38_ grams Fe +
(32x3) _96_ grams O 
(159.69x2)_319.38_ grams Fe2O3
_319.38___ grams reactants 
_319.38__ grams products

8. Mole Ratio (Coefficient Ratio)
Mole Ratio (coefficient ratio) – the ratio between the numbers of moles of any 2 substances in a balanced chemical equation
Ex. Balance the following equation and determine all mole ratios:
____ N2(g) + ____ H2(g)  ____ NH3(g)
____ Fe(s) + ____ H2O(l)  ____ Fe3O4(s) + ____ H2(g)