Stoichiometry: Rapid Review for AP Chemistry

For a more thorough review, refer to these concepts:

• Moles, Molar Mass, and Molarity for AP Chemistry
• Percent Composition and Empirical Formulas for AP Chemistry
• Reaction Stoichiometry for AP Chemistry
• Limiting Reactants for AP Chemistry
• Percent Yield for AP Chemistry

Rapid Review

• The mole is the amount of substance that contains the same number of particles as exactly 12 g of carbon-12.
• Avogadro's number is the number of particles per mole, 6.022 × 10²³ particles.
• A mole is also the formula (atomic, molecular) mass expressed in grams.
• If you have any one of the three—moles, grams, or particles—you can calculate the others.
• The empirical formula indicates which elements are present and the lowest whole-number ratio.
• The molecular formula tells which elements are present and the actual number of each.
• Be able to calculate the empirical formula from percent composition data or quantities from chemical analysis.
• Stoichiometry is the calculation of the amount of one substance in a chemical equation by using another one.
• Always use the balanced chemical equation in reaction stoichiometry problems.
• Be able to convert from moles of one substance to moles of another, using the stoichiometric ratio derived from the balanced chemical equation.
• In working problems that involve a quantity other than moles, sooner or later it will be necessary to convert to moles.
• The limiting reactant is the reactant that is used up first.
• Be able to calculate the limiting reactant by the use of the mol/coefficient ratio.
• Percent yield is the actual yield (how much was actually formed in the reaction) divided by the theoretical yield (the maximum possible amount of product formed) times 100%.
• A solution is a homogeneous mixture composed of a solute (species present in smaller amount) and a solvent (species present in larger amount).
• Molarity is the number of moles of solute per liter of solution.
• Be able to work reaction stoichiometry problems using molarity.
• Always use the balanced chemical equation in reaction stoichiometry problems.