1. Chapter 11: Stoichiometry
Section 1: Defining Stoichiometry

2. Particle and Mole Relationships
The study of quantitative relationships between the amounts of reactants used and amounts of products formed by a chemical reaction is called stoichiometry.
Based on the Law of Conservation of Mass…matter is neither created nor destroyed in a chemical reaction.
Mass of reactants = Mass of products

3. Stoichiometry Relationships Derived From a Balanced Chemical Equation
4Fe(s) O2(g)  Fe2O3(s)
Iron Oxygen  Iron (III) Oxide
4 atoms of Fe molecules O2  molecules Fe2O3
4 moles Fe moles O  moles Fe2O3
223.4g Fe g O  g Fe2O3
319.4g reactants  g products

4. Mole Ratios
The coefficients in a balanced chemical reaction indicate the relationships between moles of reactants and products.
We can use this information to derive conversion factors called mole ratios.
A mole ratio is a ratio between the number of moles of any two substances in a balanced chemical reaction.

5. Mole Ratios
2K(s) + Br2(l)  2KBr(s)

6. Chapter 11 Section 3
Limiting Reactants

7. Limiting and Excess Reactants
The limiting reactant in the reaction limits the extent of the reaction and thereby determines the amount of product formed.
A portion of all the other reactants remain after the reaction stops. Reactants left over when the reaction stops are excess reactants.

8. Determining the Limiting Reactant
These problems are very similar to stoichiometry problems…they follow the same steps.
In this case, you will be given two starting amounts and have to determine which reactant is limiting.

9. Example 1
If g of sulfurs reacts with g of chlorine, what mass of disulfide dichloride is formed?
S8(l) + 4Cl2(g)  4S2Cl2(l)

10. Example 2
Determine the mass of P4O10 formed if 25.0 g of P4 and g of O2 are combined.
P4(s) + 5O2(g)  P4O10(s)