Chemistry 111 1st Edition Exam # 3 Study GuidePercent CompositionThe composition of a compound expressed in terms of percentage by mass of each elementMass of element in compound x 100% mass of compoundEmpirical FormulaBased on the lowest whole number ratio of its component elementsExample:C4H8 reduces to CH2Na2O2 reduces to NaOEmpirical Formula vs Molecular FormulaEmpirical Formula:-Simplest whole-number ratio of elements in a compoundMolecular Formula:-Actual molar ratio of elements in a compound-Equal to whole number multiple of empirical formula-Need empirical formula and molecular formulaIf the molar mass is 26 g/mol, what is the molecular formula?Molar mass / empirical formula = 26 g / 134.44 = 2Percent YieldTheoretical Yield:The maximum amount of product possible in a chemical reaction for given reactant quantitiesActual Yield:Percent Yield = (Actual Yield / Theoretical Yield) x 100%Solutions: homogenous mixtures of two or more substancesSolvent: component of a solution that is presentSolute: any component in a solution other than the solventAmount of solute in a solution:Amount of Solute / Amount of SolventMolarity (M)M= (moles of solute/liter of solution) = n / v*As a conversion factor  g of soluteMass of solute = (volume x molarity) x Mg = (L x mol / L) x g/molDilutionsStock SolutionA concentrated solution of a substance used to prepare solutions of lower concentrationStandard SolutionA solution whose concentration is fairly precisely knownDilutionProcess of lowering the concentration of a solution by adding more solvent(# moles solute) stock = (# moles solute) diluteElectrolytesStrong Electrolytes: (Na, K)-Nearly 100% dissociated into ions-Conduct current efficientlyWeak Electrolytes (weak acids)-Only partially dissolved into ions-Slightly conductiveCH3CO2H  CH3CO2 (aq) + H (aq)NonelectrolytesSubstances in which no ionization occurs; no conduction of electrical currentAcid-Base Reactions:Acids: produce H3O in solutionBases: produce OH in solution*H3O simplified by leaving out water, often written just as HBronsted-Lowry definitions:Acids: proton (H) donorsBases: proton acceptorsHCl (donor/ acid) + H2O (acceptor / base)  H3O + ClStrong Acids / Bases:Dissociate completely in aqueous solutionStrong Acids: HCl, HBr, HI, H2SO4, HNO3, HClO4Examples:H2SO4 H + HSO4HNO2 H + NO2Strong BasesNaOH  Na + OHWeak BasesNH3 + H2O  NH4 + OHWater as a Base:HCl (donor) + H2O (acceptor)  H3O + ClNeutralizationReaction that takes place when an acid reacts with a base producing a solution of salt in waterSaltPb (NO3)2 (aq) + 2NaI (aq)  PbI2 (s) + 2 NaNO3 (aq)Saturated SolutionA solution that contains the maximum concentration of solute possible at a given temperatureSupersaturated SolutionContains more than the maximum quantity of solute predicted to be soluble in a given volume of solution at a given temperatureOxidation – Reduction ReactionsOxidationReaction that increases oxygen content of a substance (loss of electrons)4Fe (s) + 3O2 (g)  2Fe2O3ReductionReaction involving loss of O2 (gain electrons)Fe2O3 (s) + 3CO (g)  2Fe (s) + 3CO2REDOX: transfer of