Chem 1ALecture 8HomeworkRead chapter 4 ALEKS homework: XM4NG-QNDN6Chapter 4 book problemsRecap• Balancing Chemical Equations• Reading Chemical Equations• Combustion Reactions• Limiting ReagentsN2 + 3H2  2NH3a) If if we combine 100 g of N2and 30 g of H2which is the limiting reagent?b) How much NH3is produced (in grams) assuming the reaction goes to completion? This is called the theoretical yield.Theoretical YieldN2 + 3H2  2NH3Do experiment: We combine 100 g of N2and 30 g of H2, and reaction produces 105.7 g of NH3.Calculate the percent yield.Percent YieldTo summarize:• Limiting reactant (or limiting reagent)—the reactant that is completely consumed in a chemical reaction• Theoretical yield—the amount of product that can be made in a chemical reaction based on the amount of limiting reactant• Actual yield—the amount of product actually produced by a chemical reaction.• Percent yield—(actual yield/theoretical yield)×100%Solution – is a homogeneous mixture of two or more substances.Solvent - is the component that is present in greater quantity.Solute - is the component that is present in lesser quantity. It is said to be dissolved in the solvent. Aqueous Solutions – Solutions where water is the solvent.A compound is soluble in a particular liquid if it dissolves in that liquid. A compound is insoluble if it does not dissolve in the liquid.When ionic compounds dissolve in water, they usually dissociate into their component ions. SolutionWaterNaCl vs. WaterWater is a polar solvent.NaCl(s)  Na+(aq) + Cl-(aq)MgCl2(s)  Mg2+(aq) + 2 Cl-(aq)MgSO4(s)  Mg2+(aq) + SO42-(aq)Ionic Compounds in WaterA. CaBr2B. NaNO3C. C6H12O6D. Two are strong electrolytesE. All of the aboveWhich of the following compounds is a strong electrolyte?A. CaBr2B. NaNO3C. C6H12O6D. Two are strong electrolytesE. All of the aboveWhich of the following compounds is a strong electrolyte?Electrolyte – a substance whose aqueous solutions contains ions and hence conduct electricity.Non electrolyte - a substance that does not form ions in solution. Aqueous SolutionsCH3CO2H (aq) ⇋ CH3CO2 -(aq) + H+(aq) Aqueous SolutionsStrong Electrolyte: Substance dissociates ~100%Producing lots of ions in solution.Weak Electrolyte: Substance dissociates a littleProducing a few ions in solutionNon Electrolyte: Substance may dissolveProduces no ions in solution ElectrolytesSolute dissolves in solventIf solvent is water => aqueous solutionM = Molarity =Use square brackets: [HCl] = 1.0 Msolution ofLiter solute of molesSolutionsSolution: 3.0 M CaCl2(aq) What is the concentration of Ca2+ and Cl–?[CaCl2] = 3.0 M[Ca2+] = ?[Cl–] = ?ExampleExample:You have 6.0 M HCl in stock.You want 50.0 mL of 2.0 M HCl.What volume of 6.0 M HCl is needed?Diluting SolutionsInitial: H2O Final:6.0 M HCl  2.0 M HClV= ? 50.0 mLInitial moles solute = Final moles soluteninitial= nfinalM1V1= M2V2Making Solutions• Not all ionic compounds dissolve in water. • AgCl does not dissolve in water. • AgCl remains as a solid, AgCl(s), within the liquid water.• It does not dissolve into independent ions.Ionic Compounds in WaterTypes of Chemical Reactions and Solution Stoichiometry Reactions in aqueous solution. Aqueous => waterSolubilitySolubilitySolubilityKCl(aq) + AgNO3(aq)Observe white precipitateWhat is the precipitate?PrecipitationFrom the Greek, “To Transpose”AX + BY  AY + BXAgNO3(aq) + KCl(aq)  AgCl(s) + KNO3(aq)For a metathesis reaction to occur, ions must be removed from the solution.1. The formation of an insoluble solid (a precipitate).2. The formation of either a soluble weak electrolyte or soluble nonelectrolyte.3. The formation of a gas. Metathesis Reactions• The cation from one compound can now pair with the anion from the other compound to form new (and potentially insoluble) products. If the potentially insoluble products are both soluble,then no reaction occurs.If one or both of the potentially insoluble products are insoluble, a precipitation reaction occurs. Precipitation Reactions1. Write and equation with the reactants and then combine the cation from one reactant with the anion from the other. **Make sure to write correct (charge-neutral) formulas for the new ionic compounds.**2. Use the solubility rules to determine whether any of the potential new products are indeed insoluble.3. If all of the potentially insoluble products are soluble, there will be no precipitate. Write NO REACTION next to the arrow.4. One of the potentially insoluble products is insoluble, so write its formula as the product of the reaction, using (s) to indicate solid. Write the soluble product with (aq) to indicate aqueous.5. Balance the equationPrecipitation ReactionsMolecular Equation:Mg(NO3)2(aq) + 2NaOH(aq)  Mg(OH)2(s) + 2NaNO3(aq) Complete Ionic Equation:Mg2+(aq) + 2NO3-(aq) + 2Na +(aq) + 2OH-(aq)  Mg(OH)2(s) + 2Na +(aq) + 2NO3-(aq)Spectator Ions – Are ions that appear in identical forms among both the reactants and the products. EquationsWhen spectator ions are omitted from the complete ionic equation, we are left with the net ionic equation.Complete Ionic Equation:Mg2+(aq) + 2NO3-(aq) + 2Na +(aq) + 2OH-(aq)  Mg(OH)2(s) + 2Na +(aq) + 2NO3-(aq)Net Ionic Equation:Mg2+(aq) + 2OH-(aq)  Mg(OH)2(s) Net Ionic EquationWrite the net ionic equations for the reactions that occur when solutions of the following compounds are mixed.a) KOH and Co(NO3)2 b) NaCl and (NH4)2SO4PracticeA. KNO3(s)B. N3–(aq)C. PbI2(aq)D. PbI(s) E. None of the aboveWhich of the following is a term in the complete ionic equation for the following reaction?KI(aq) + Pb(NO3)2(aq) →A. KNO3(s)B. N3–(aq)C. PbI2(aq)D. PbI(s) E. None of the aboveWhich of the following is a term in the complete ionic equation for the following reaction?KI(aq) + Pb(NO3)2(aq) →A. Li+and H+B. Li+and NO3–C. Li+and OH–D. H+and OH–E. All of the aboveWhat are the spectator ions for the following reaction?LiOH(aq) + HNO3(aq) →A. Li+and H+B. Li+and NO3–C. Li+and OH–D. H+and OH–E. All of the aboveWhat are the spectator ions for the following reaction?LiOH(aq) + HNO3(aq) →a) 0.6 molb) 0.2 molc) 0.4 mold) 0.13 mole) 0.07 molWhen 100.0 mL of 2.0 M Al(NO3)3is added to 200.0 mL of 2.0 M KOH, how many moles of Al(OH)3can be produced