1. AP Chemistry Zumdahl Notes, 9th ed.
A Brief Collection of notes, Chapter 3
Feel free to open these files and annotate as you feel the need…this is
for your success.

2. Stoichiometry
Counting by weighing…do you really think you can count atoms?
Atomic masses
AMU: one-twelfth of a carbon-12 atom
Atomic mass: weighted avg. of naturally occurring isotopes
The Mole: using Avogadro’s number
Think “just another conversion”
Molar Mass: appropriate calculation using subscripts as multipliers
Percent Composition of Compounds
Mass percent: remember must total 100%
Mass component/mass total x 100 = %component
Determination of Formula: assume 100 g of material, convert to g, divide by appropriate atomic masses to find moles, divide all by smallest to get ratio. This will give empirical formula, which may or may not be the molecular formula

3. Stoichiometry Chemical Equations Balancing Chemical Equations
Reactants produce products
Balancing Chemical Equations
Can change coefficients in front of reactants and products, but cannot change subscripts, as this changes these compounds
Look for elements with multiples on different sides…must find coefficients such that they will be equal on both sides
If polyatomic ions are on both sides, keep them intact…makes your counting that much easier

4. Stoichiometry Amounts of Reactants and Products
Before you can solve virtually any stoichiometry problem, you must take what information you are given and convert it into moles; then, find the appropriate mole ratio for what you need, then modify your output into the format needed
Limiting Reactant: which one can determine how far your reaction if allowed to progress? Again, need to convert all info into moles, then determine, using DA/factor label, which one is limiting; now, base all calculations on this, as it controls outputs; can be determined with either reactants or products, just means that your approach is from a different direction

5. Stoichiometry
Yield Calculations: based upon limiting reactant/s, this is what could be produced if reaction goes 100% (theoretical yield).
Percent yield = (actual yield)/(theoretical yield) x100%
Reality check…cannot be over 100% 
I think one of the things to always remember about the different stoichiometric calculations is that you should be able to back-track and show your pathway to your answer. It is always a series of logical steps.