Chapter 7 (Chemical Reactions): Evidence a chemical reaction may have occurred: Balancing chemical equations: Standard reactions: • Obeys Law of Conservation of Mass Example: 6KOH + 1Co3(PO4)2 2K3PO4 + 3Co(OH)2 Combustion reactions of a hydrocarbon: • O2 is always a reactant and CO2 & H2O are always products. Example: C4H10 + 13/2 O2  4 CO2 + 5 H2O • Fractional coefficients OK only on diatomic molecules Types of chemical reactions:Chapter 8 (Quantities in Chemical Reactions): Mole " Mole conversions using chemical equations as guide: N2 + 3H2 → 2NH3 Mass " Mass conversions using chemical equations: • Assumes an excess of all but one reactantLimiting reagent: • The reactant that is completely consumed (first) in a chemical reaction. • Assumes no excess of any reactant Theoretical Yield: • The theoretical amount of product that can be made in a chemical reaction based upon the amount of the limiting reactant (usually in g). Actual Yield: • The actual amount of product isolated from the chemical reaction (usually in g) Percent Yield: • Enthalpy of Reaction (∆Hrxn): • Used in Thermochemical Equations o Describes the amount of thermal energy which flows during a chemical