UnitUnit IV:IV: ChemicalChemical EquationsEquations && StoichiometryStoichiometry
A. TheThe chemicalchemical equationequation B. TypesTypes ofof chemicalchemical reactionsreactions A. ActivityActivity seriesseries ofof metalsmetals B. SolubilitySolubility rulesrules C. RulesRules forfor writingwriting andand balancingbalancing equationsequations D. CalculationsCalculations fromfrom chemicalchemical equationsequations E. LimitingLimiting reactantreactant F. ApplicationsApplications ofof stoichiometrystoichiometry G. TheoreticalTheoretical andand percentpercent yeildyeild TheThe ChemicalChemical EquationEquation WordWord equations:equations:
SolidSolid potassiumpotassium chlorate,chlorate, whenwhen heated,heated, decomposesdecomposes toto produceproduce solidsolid potassiumpotassium chloridechloride andand oxygenoxygen gas.gas.
ChemicalChemical equation:equation: ∆
22 KClOKClO3(s) 2KCl2KCl(s) ++ 33 OO2(g)
4-A TheThe ChemicalChemical EquationEquation
Convert the following word equations into a chemical equation:
Aqueous silver nitrate reacts with aqueous strontium chloride to form a silver chloride precipitate and a solution of aqueous strontium nitrate.
Solid iron (III) oxide and aluminum powder are heated and react to form solid aluminum oxide and liquid iron. Classes of Chemical Reactions
Combination Decomposition Single Replacement Double Replacement – Neutralization Combustion Evidence for a Chemical Change
Heat being released (exothermic) or absorbed (endothermic) Light is given off Color change Evolution of gas Precipitate forms when solutions are mixed Formation of new substances CombinationCombination (synthesis)(synthesis) ReactionReaction GeneralGeneral formform ofof combinationcombination reactionreaction AA ++ BB CC
Ex.Ex. IronIron andand oxygenoxygen
2Fe2Fe(s) ++ 3O3O2(g) 2Fe2Fe2OO3(s) DecompositionDecomposition ReactionReaction
GeneralGeneral formform ofof thethe equationequation ABAB AA ++ BB
AnAn exampleexample wouldwould bebe nitrogennitrogen triiodidetriiodide
22 NINI3 (s)(s) →→ NN2 (g)(g) ++ 33 II2 (g)(g)
Demonstration SingleSingle ReplacementReplacement ReactionReaction AA ++ BDBD ADAD ++ BB
HereHere AA representsrepresents aa metal,metal, BB aa metalmetal ionion andand DD anan anion.anion. IfIf AA isis moremore activeactive thanthan BB itit willwill replacereplace it.it.
Ex.Ex. AluminumAluminum ++ IronIron (III)(III) oxideoxide
Demonstration ActivityActivity seriesseries
Most Reactive 2+ + MgMg MgMg HH2(g) 2H2H (aq) AlAl AlAl3+ CuCu CuCu2+ ZnZn ZnZn2+ AgAg AgAg+ FeFe FeFe2+ HgHg HgHg2+ NiNi NiNi2+ AuAu AuAu3+ SnSn SnSn2+ Least Reactive PbPb PbPb2+ DoubleDouble ReplacementReplacement ReactionReaction GeneralGeneral formform ofof thethe equationequation ABAB ++ CDCD ADAD ++ CBCB TheThe cationcation andand anionanion ofof oneone compoundcompound switchswitch withwith thosethose ofof anotheranother
Ex.Ex. MercuryMercury (II)(II) chloridechloride andand sodiumsodium iodideiodide
Demonstration SolubilitySolubility RulesRules AllAll compoundscompounds withwith GroupGroup IAIA oror NH4NH4+ cationscations areare solublesoluble inin waterwater AllAll compoundscompounds withwith nitratenitrate andand acetateacetate anionsanions areare solublesoluble inin waterwater AllAll halideshalides (F(F-,, ClCl-,, BrBr-,, II-)) areare solublesoluble exceptexcept inin + 2+ 2+ compoundscompounds withwith AgAg ,, PbPb ,, HgHg2 AllAll sulfatessulfates areare solublesoluble exceptexcept withwith BaBa2+,, SrSr2+,, CaCa2+,, andand PbPb2+
SeeSee thethe TableTable onon pagepage 109109 ofof youryour manualmanual forfor aa moremore completecomplete listlist ofof somesome solubilitysolubility rulesrules CombustionCombustion ReactionReaction
GeneralGeneral equation:equation:
HydrocarbonHydrocarbon ++ OO2 COCO2 ++ HH2OO
TheThe oxygenoxygen cancan comecome fromfrom aa varietyvariety ofof sourcessources
Ex.Ex. OxidationOxidation ofof glyceringlycerin
14 KMnO4 + 4 C3H5(OH)3 7 K2CO3 + 7 Mn2O3 + 5 CO2 + 16
H2O Demonstration Lecture Problems 4-1 pg. 111
Write complete chemical equations for the following and include their classification
a. Al (s) + O2 (g) aluminum oxide b. ammonia gas hydrogen gas + nitrogen gas c. C6H12 (l) + oxygen gas CO2 (g) + H2O (g) d. (NH4)2SO4 (aq) + BaCl2 (aq) barium sulfate (s) + ammonium chloride (aq)
Extra practice: Al (s) + copper (II) sulfate (aq) copper (s) + aluminum sulfate (aq) Rules for Balancing Equations
1.Write the correct formulas for reactants and products. 2.Count and compare the number of atoms of each element on both sides of the equation 3.Balance the elements one at a time, by using stoichiometric coefficients in front of the necessary compounds.
Remember! Never change the actual formula of a compound to balance the equation Rules for Balancing Equations
4. Start with the most complicated compound first. (The one with the most atoms) 5. Make sure as you work through each element you note any others that become unbalanced. 6. Try balancing oxygen and hydrogen last. 7. Polyatomic groups that are not changed during the reaction are balanced as groups. 8. The numbers used (stoichiometric coefficients) to balance an equation should be in the smallest ratio possible. Lecture Problem IV-2 (pg. 113)
a. __Fe(s) + __O2(g) –> __Fe2O3(s)
Solid iron combines with oxygen gas to form solid iron (III) oxide.
b. __Mg(s) + __N2(g) –> ______(s)
Solid magnesium reacts with nitrogen gas to form solid magnesium nitride
d. __Co2(CO3)3(s) –>__Co2O3(s) + __CO2(g) Solid cobalt (III) carbonate decomposes to form solid cobalt (III) oxide and carbon dioxide gas
f. __AgClO3(s) –> __AgCl(s) + __O2(g) Solid silver chlorate decomposes to form solid silver chloride and oxygen gas Lecture Problem IV-2 (pg. 114) h. __Sn(s) + __HCl(aq) –> __SnCl2(aq) +__H2(g) Tin metal reacts with hydrochloric acid to form aqueous tin (II) Chloride and hydrogen gas. j. __P4(s) + __N2O(g) –> __P4O6(s) + __N2(g) Solid phosphorus reacts with dinitrogen monoxide to form solid Tetraphosphorus hexaoxide and nitrogen gas. l. __Pb(C2H3O2)2(aq) + __KI(aq)–>___(s) + __KC2H3O2(aq) Aqueous lead (II) acetate reacts with aqueous potassium iodide to form a solution of potassium acetate and a precipitate of lead (II) iodide. o. __H2SO4(aq) + __KOH(aq)–> __K2SO4(aq) + __H2O(g) Sulfuric acid is neutralized with potassium hydroxide to form a solution of potassium sulfate. Lecture Problem IV-2 (pg. 115)
q. __C8H18(l) + __O2(g) –> ____(g) +__H2O(g)
Liquid octane is burned in oxygen gas to form gaseous carbon dioxide and water vapor.
r. __NH3(g) + __O2(g) –>__NO2(g) + __H2O(g) Gaseous ammonia reacts with oxygen to form nitrogen dioxide gas and gaseous water. Extra Practice: Complete the Following
Magnesium metal reacts with H2SO4(aq) → …
CH3(CH2)3CH2OH + oxygen gas → …
NaHCO3 + HCl(aq) → aqueous sodium chloride + water + carbon dioxide gas. Sulfur and oxygen combine when heated to form sulfur dioxide gas.
MgCO3 + heat → MgO + …
AgNO3(aq) + NaCl(aq) → ...