You have a test tomorrow over the more difficult concepts in Ch. 10 and Ch. 12. Here are some videos that discuss these concepts to help you review.
Using the mole mathematically (basic conversions from Ch. 10):
Percent composition & empirical/molecular formulas:
Stoichiometry (mole ratios, going from grams of a reactant to grams of a product, theoretical yield, etc.):
Limiting reactants in stoichiometry: