3 Types of Reactions Combination (Synthesis) Decomposition Combustion Single ReplacementDouble Replacement (Metathesis)
4 Combination/Synthesis Basic FormA + B ABRxns of elements with oxygen and sulfurC(s) + O(s) CO2 (g)Rxns of metals with halogens2Na(s) + Cl2 (g) 2NaClSynthesis rxns with oxidesCaO(s) + H2O (l) Ca(OH)2 (s)
5 Decomposition Basic Form AB A + B Binary compounds 2H2O (l) 2H2 (g) + O2 (g)Metal hydroxidesCu(OH)2 (s) CuO(s) + H2O (l)
6 More Decomposition Examples Metal carbonatesPbCO3 (s) PbO (s) + CO2 (g)Metal chlorates2KClO3 (s) 2KCl (s) + 3O2 (g)OxyacidsH2CO3 (l) H2O (l) + CO2 (g)
7 CombustionA substance combines with oxygen, releasing a large amount of energy in the form of light and heat.True or False: The products of every combustion reaction are CO2 and H2OFalse
8 Combustion Examples Reactive elements combine with oxygen P4(s) + 5O2(g) P4O10(s)(This is also a synthesis reaction)The burning of natural gas, wood, gasolineC3H8(g) + 5O2(g) 3CO2(g) + 4H2O(g)
9 Single Replacement Basic Form A + BY AY + B Metals by other metals 3Mg + 2FeCl3 2Fe + 3MgCl2Hydrogen in water by another metal2Na +2H2O H2 + 2NaOH
10 More Single Replacement Hydrogen in an acid by another metal2Li + 2HCl H2 + 2LiClHalogens by more active halogensCl2 + 2KI I2 + 2KCl
11 The Activity Series of the Metals LithiumPotassiumCalciumSodiumMagnesiumAluminumZincChromiumIronNickelLeadHydrogenBismuthCopperMercurySilverPlatinumGoldMetals can replace other metalsprovided that they are above themetal that they are trying toreplace.Metals above hydrogen canreplace hydrogen in acids.Metals from sodium upward canreplace hydrogen in water
12 The Activity Series of the Halogens FluorineChlorineBromineIodineHalogens can replace otherhalogens in compounds, providedthat they are above the halogenthat they are trying to replace.2NaCl(s) + F2(g) 2NaF(s) + Cl2(g)MgCl2(s) + Br2(g) ???No Reaction
13 Double Replacement (Metathesis) Basic FormAX + BY AY + BXOne of the compounds formed is usually a precipitate, an insoluble gas that bubbles out of solution, or a molecular compound, usually water.How do you tell if a precipitate will form?Use your Solubility Rules!!!
15 Mostly Insoluble Ion Solubility Exceptions CO32- Insoluble Group IA and NH4+PO43-OH-Group IA and Ca2+, Ba2+, Sr2+S2-Groups IA, IIA, and NH4+
16 The Solubility Rule Song!!!! (Sing to Rhythm of 99 Bottles) Alkali metals and ammonium salts,Whatever they may be,Can always be depended on for solubilityWhen asked about the nitratesThe answer is always clear,They each and all are soluble,Is all we want to hear.Most every chloride's solubleAt least we've always readSave silver, mercury oneAnd chloride of leadEvery single sulfateIs soluble, 'Tis said'Cept barium, strontium, mercury one And calcium and lead.-Hydroxides in generaldon't dissolve at allBut, barium, strontium and calciumAre slightly soluble*but don't forget *Alkali metals and ammonium saltsWhatever they may beCan always be depended onFor solubility The carbonates are insoluble,It's lucky that it is so,Or else, our marble buildingsWould melt away like snow.*but, once again, don't forget *For solubility
17 Spectator Ions do NOT participate in the reaction Net Ionic EquationsWritten to show only the species that react or undergo change in aqueous solution.Steps for writing net ionic equationsWrite a balanced molecular equationRewrite the equation to show the ions that form in solutionIdentify and cancel spectator ionsSpectator Ions do NOT participate in the reaction
18 Sample ProblemWhat compound precipitates when solutions of Fe2(SO4)3 and LiOH are mixed? Write the complete chemical reaction for the reactants above. Write the net ionic equation. List any spectator ions.
19 Another Type of Metathesis Acid/Base ReactionsTwo TypesNeutralizationHCl + NaOH NaCl + H2OGas Formation2HCl +Na2S H2S(g) + 2NaClHCl + NaHCO3 NaCl + H2CO3H2CO3 H2O + CO2(g)
21 Redox Rxn Each sodium atom loses one electron atom gains one electron: Each chlorine atom gains one electron:
22 LEO says GER :Lose Electrons = OxidationSodium is oxidizedGain Electrons = ReductionChlorine is reduced
23 OIL RIG:Oxidation Is Loss of electronsSodium is oxidizedReduction Is Gain of electronsChlorine is reduced
24 Reducing Agents and Oxidizing Agents The substance reduced is the oxidizing agentThe substance oxidized is the reducing agentSodium is oxidized – it is the reducing agentChlorine is reduced – it is the oxidizing agent
25 Rules for Assigning Oxidation #s Atoms in elemental form are always zeroMonatomic ions equal the charge on the ionOxygen is usually -2 (except peroxide is -1)Hydrogen is +1 with NM and -1 with MFluorine is always -1Sum of the ox #s of all atoms in a neutral compound is zeroSum of the ox #s in a polyatomic ion = the ion charge
26 Sample Problem H2S S8 SCl2 Na2SO3 SO42- Determine the oxidation #s for the following:H2SS8SCl2Na2SO3SO42-
27 Oxidation of metals by acids and salts Similar to single replacement rxns, sometimes called Displacement RxnsGeneral formA + BX AX + BExamplesZn(s) + 2HBr (aq) ZnBr2(aq) + H2 (g)Mn(s) + Pb(NO3)2(aq) Mn(NO3)2 (aq)+ Pb(s)
28 Rules for Balancing Redox Rxns Assign oxidation #sDetermine which species are being oxidized or reducedDivide the equation into 2 half-reactionsBalance each half reactionBalance elements other than H and OBalance O by adding water as neededBalance H by adding H+ as neededBalance charge by adding e-Multiply half reactions by integers so # of e- are the same in each reactionAdd half reactions together, simplifying when you canCheck to see if equation is charge and mass balanced
29 Sample Problem Balance the following MnO4-(aq) + C2O42-(aq) Mn2+(aq) + CO2(aq)
30 Other Rxns Metal Oxide in Water Nonmetal Oxide in Water MO + H2O MOH BaO + H2O Ba(OH)2Nonmetal Oxide in WaterNO + H2O oxyacidN2O3 + H2O HNO2
32 Solute Solvent A solute is the dissolved substance in a solution. Salt in salt waterSugar in soda drinksCarbon dioxide in soda drinksSolventA solvent is the dissolving medium in a solution.Water in salt waterWater in soda
33 Definition of Electrolytes and Nonelectrolytes An electrolyte is:A substance whose aqueous solution conductsan electric current.A nonelectrolyte is:A substance whose aqueous solution does notconduct an electric current.Try to classify the following substances aselectrolytes or nonelectrolytes…
34 Which of the following are electrolytes? Pure waterTap waterSugar solutionSodium chloride solutionHydrochloric acid solutionLactic acid solutionEthyl alcohol solutionPure, solid sodium chloride
35 Answers… ELECTROLYTES: NONELECTROLYTES: Tap water (weak) NaCl solution HCl solution Lactate solution (weak) Pure water Sugar solution Ethanol solution Pure, solid NaCl
36 Electrolytes & Net Ionic Equations Ionic CompoundsDissociateNaCl(s) Na+(aq) + Cl-(aq)AgNO3(s) Ag+(aq) + NO3-(aq)MgCl2(s) Mg2+(aq) + 2 Cl-(aq)Na2SO4(s) 2 Na+(aq) + SO42-(aq)AlCl3(s) Al3+(aq) + 3 Cl-(aq)These compounds should be written as ions in net ionic equations.
37 Strong acids such as HCl are completely ionized in solution Strong acids such as HCl are completely ionized in solution. So they are written as ions in the net ionic equationOther examples of strong acids include:Sulfuric acid, H2SO4Nitric acid, HNO3Hydriodic acid, HIPerchloric acid, HClO4Weak acids such as lactic acid usually ionize less than 5% of the time. So they are not written as ions in the net ionic equation.
38 MolarityThe concentration of a solution measured in moles of solute per liter of solution.mol = ML
39 Sample ProblemHow many grams of sodium chloride are needed to prepare 1.50 liters of M NaCl sol’n?
40 Serial DilutionIt is not practical to keep solutions of many different concentrations on hand, so chemists prepare more dilute solutions from a more concentrated “stock” solution.MstockVstock = MdiluteVdilute
41 Sample ProblemWhat volume of stock (11.6 M) hydrochloric acid is needed to prepare a 3.0 M ml solution?
42 Sample ProblemHow many grams of Ca(OH)2 are needed to neutralize 25.0 mL of M HNO3?
43 Sample ProblemA sample of 70.5 mg of potassium phosphate is added to 15.0 mL of M silver nitrate, resulting in the formation of a precipitate.Write the molecular equation for the reactionWhat is the limiting reactant?Calculate the theoretical yield, in grams, of the ppt that forms.
44 Sample Problem45.7 mL of H2SO4 is required to neutralize a 20.0 mL sample of NaOH solution. What is the concentration of the NaOH solution?