Chapter 15: Acids and Bases Part IIConjugate Acids and BasesConjugates ContinuedSmall Highly Charge Metal CationsExamplesClassifying Salts as Acidic Basic or NeutralPowerPoint PresentationSlide 8ExampleSlide 10Lewis Acids and BasesSlide 12Chapter 15 1Chapter 15: Acids and BasesPart IIGeorgia Gwinnett CollegeChem 1212KFall 2013(B. Shepler)Conjugate Acids and Bases•The conjugate of an acid (often an anion) can act as a base.–The stronger the acid, the weaker is its conjugate base.•The conjugate of a base (often a cation) can act as an acid.–The stronger the base, the weaker is its conjugate acid.•The Ka and Kb of a conjugate acid/base pair are related.Chapter 15 2Ka´ Kb=KwConjugates Continued•Conjugates of Acids–The conjugate of a strong acid is neutral.–The conjugate of a weak acid is a weak base•Conjugates of Bases–The conjugate or counter ion of a strong base is neutral–The conjugate of a weak base is a weak acid–Small highly charged cations are weak acidsChapter 15 3Small Highly Charge Metal Cations•Most cations except alkali metals and alkaline earth metals from slightly acidic solutions.Al3+(aq) + 6H2O(l)  Al(H2O)63+(aq)Chapter 15 4Examples•Classify the following anions as a weak base or neutral.C2H3O2−NO3−SO2−Cl−•Classify the following cations as a weak acid or neutral.Na+Fe3+CH3NH3+Chapter 15 5Classifying Salts as Acidic Basic or Neutral•Consider the cation and anion individually–Determine whether the anion is basic or neutral–Determine whether the cation is acidic or neutral–If anion is basic and cation is acidic then compare their Kb and Ka. The larger one wins.•Remember that the relationship KaxKb=Kw only works for conjugate pairs. However, you can use this if you only know the dissociation constant of one half of a conjugate pair.Chapter 15 6Chapter 15 7Chapter 15 8Example•Classify the following as acidic, basic or neutral.SrBr2Ba(C2H3O2)2Cr(NO3)2NH4ClNH4ClOChapter 15 9Example•Calculate the pH of 0.30 M RbNO2Chapter 15 10Lewis Acids and Bases•We have a third definition of acids and bases that is still broader than the Bronsted-Lowry Definition.•Lewis Acids and Bases:–A Lewis acid: Electron pair acceptor–A Lewis base: Electron pair donor•Examples–H+ + NH3–BF3+NH3Chapter 15 11Example•Classify each species as a Lewis Acid or Lewis Base.Fe+3NH3CN-•Identify the Lewis acid and Lewis base from the reactants.Fe3+(aq) + 6H2O(l)  Fe(H2O)63+(aq)(CH3)3N(g) + BF3(g) (CH3)3NBF3(s)Chapter 15