CHEM 1211 Lecture 9Outline of Last Lecture I. Chemical EquilibriaII. Types of Reactions A. Precipitation B. Acid-Base NeutralizationC. Gas FormingD. Reduction-OxidationIII. Classifying RXNsOutline of Current Lecture I. Example ReactionsA. Clicker QuestionsII. Chemical CalculationsA. Mom’s Pound CakeIII. Conceptual UnderstandingCurrent LectureI. Example Reactions1. A student precipitates Ca(OH)2. The precipitate is gelatinous and hard to manage. What do we do to make it more manageable?- Heat Metal OxideSolid Calcium Oxide reacts with waterCaO(s) + H2O(l) Ca(OH)2(s).2. Barium Hydroxide: Strong Base RXNs Produced: acid-base, exchange, Sulfuric Acid: Strong Acid precipitation3. Silver/Copper DemonstrationOxidized: Cu(s) Cu2+(aq) + 2e-Reduced: 2(Ag+(aq) + e- Ag(s))REDOX RXN: 2 Ag+(aq) + Cu(s) Cu2+(aq) + 2Ag(s)4. H2O2(aq) + I-(aq) O2(g) + H2O(l) + I-(aq)H2O2= Hydrogen Peroxide: Total Charge of 0.I-= catalyst, not spectator ionsO2: Normal charge of -2H: oxidation state = +1***Redox RXN or gas-forming RXN. H OTotal Charge: 0 = 2(+1) + 2(x) Finding the charge of ion in a compound X = -1 when we know the total charge+1-1 0 +1-2H2O2(aq) + I-(aq) O2(g) + H2O(l) + I-(aq) Ox. Red.H2O2: normally the oxidizing agent, but here it is the ox. and red. agent.A. Clicker Questions1. Acetic Acid reacts with Barium hydroxide. The total ionic equation is?2CH3CO2- + Ba2+ + 2HO- 2CH3CO2- + Ba2+ + H2OKeep ions together, don’t break apart weak electrolytes2. Which represents an oxidation process?Fluoride ion converted into FluorineOx= loss of e-: Charge is pos. LEO goes GERRed= Gain of e-Oxidizing agent takes away e-II. Chemical Calculations- Chemical arithmetic is like cookingA. Mom’s Pound Cake- ½ pound (2 sticks) butter - ½ tsp. fine salt- ½ cup veg. shortening - ½ tsp. baking powder- 3 cups sugar - 1 cup milk- 5 eggs - 1 tsp. Vanilla extract- 3 cups flour9 cups of flour 3 cakes Clicker Q #3: How many cakes can we 6 cups of suger 2 cakes Make? 2!20 eggs 4 cakes Reactants Products2 ½ tsp. of vanilla 2.5 cakesIII. Conceptual Understanding1. 2H2 + O2 2H2OLimiting Reagent: O2 … Still have some H2
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