CHAPTER 8 OUTLINE CHEMICAL REACTIONS
	I. Describing Chemical Change      A. Word Equations           1. Review: Chemical reaction, one or more substances (reactants) change into one or more new substances (porducts)                Reactants --> Products                a. Law of Conservation of Mass                Reactant atoms = Product atoms           2. Write reactions with words                Example --> Iron reacts with oxygen to produce iron three oxide (rust)                     Iron + Oxygen --> Iron (III) oxide      B. Chemical Equation           1. Use chemical formulas to write equations (represent chemical reactions)                Example --> Fe + O2 --> Fe2O3                a. English we use letters, words, sentences                b. Chemistry we use symbols, formulas,equations           2. Skeleton Equation --> just shows the reactants and products involved, not how much of each           3. Indicate state of matter in parenthesis after formula                a. Solid = s, Liquid = l, Gas = g, Solutions in water = aq (aqueous)           4. Catalyst --> a substance that speeds up a reaction, but does not react itself                a. Write above arrow      C. Balancing Chemical Equations           1. Balanced equation --> Reactant atoms = Product atoms           2. Word & skeleton equations only qualitative                a. Need quantitative values (balance)           3. Coefficients --> # placed in front of formulas to show amount of each substance                a. Use distributive property with coefficients           4. Rules for balancing                a. Determine correct formula for each substance                b. Reactant formulas on left of arrow, Product formulas on right of arrow                c. Count # of atoms on both sides                     1. If polyatomic ion is on both sides, consider it as one unit                d. Balance elements using coefficients                     1. Balacne metals first, nonmetals second                     2. Balance oxygen and hydrogen last                e. Check: does reactant atoms = product atoms                f. Make sure that all coefficients are smallest shole # ratio with each other II. Types of Chemical Reactions      A. Combination (Synthesis) Reaction           1. two or more substances combine to form one product           2. General form:  x  +  y  -->  xy           3. Examples:                a. metal with a nonmetal                b. nonmetal with a nonmetal                c. Nonmetal oxide with water = acid                d. Metal oxide with water = base      B. Decomposition Reaction           1. One substance is broken down into two or more substances           2. General form:  xy  -->  x  +  y           3. reguire energy (heat, light, electricity) to break bonds      C. Single Replacement (Displacement) Reaction           1. One element replaces another element in a compound           2. General form:  x  +  yz  -->  xz  +  y           3. Activity (Reactivity) Series -- order of decreasing reactivity of elements                a. Used to determine if a single replacement reaction will occur                b. More reactive metal replaces less reactive metal in compound (solution)           4. Nonmetals (usually only Halogens) decrease in reactivity as you go down the group      D. Double Replacement (displacement) Reaction           1. Two compounds exchange cations with each other           2. General form:  wx  +  yz  -->  yx  +  wz           3. Usually occurs between two ionic compounds in an aqueous solution (Lab 6)           4. Must follow one of these rules for a reaction to occur                a. formation of a precipitate (solid)                b. formation of a gas                c. Production of water      E. Combustion Reaction           1. substance reacts with oxygen to produce carbon dioxide, water, and energy           2. General form:  xy  +  O2  -->  CO2  +  H2O  +  heat      F. Predicting Products of Chemical Reactions -- see pag. 222-223 III. reactions in Aqueous Solutions      A. Net Ionic Equaitons           1. Ionic compounds dissociate (separate) in solution (aqueous)           2. Complete Ionic Equation -- equation with ions instead of ionic compounds                Ag+(aq)  +  NO3-(aq)  +  Na+(aq)  +  Cl-(aq)  -->  AgCl(s)  +  Na+(aq)  +  NO3-(aq)                a. Eliminate Spectator Ions -- Ions not involved in the reaction of the precipitate           3. Net Ionic Equation -- an equation with onl the ions involved in the formation of the precipitate                Ag+(aq)  +  Cl-(aq)  -->  AgCl(s)                a. Balance charge just like you balance atoms           4. Used for single and double replacement reactions      B. Predictiong Formation of a Precipitate           1. Use Solubility Rules for Ionic Compounds Compounds                              Solubility                              Exceptions Alkali metal salts/ammonia         Soluble (dissolves)              Some Lithium Compounds Nitrate salts/Chlorate salts         Soluble                                Few exceptions Sulfate salts                               Soluble                                Pb, Ag, Hg, Ba, Sr, Ca Carbonates, Phosphates,          Most are insoluble               Alkali metal compounds and ammonium Chromates, Sulfides, Hydroxides Outline based upon:      Matta, M. S., Staley, D. D., Waterman, E. L., & Wilbraham, A. C. (2000). Chemistry, Addison-Wesley. (5th ed.). Menlo Park, CA: Prentice Hall, pp. 203-229.                                                              Return Home