CHEM160 General Chemistry II Lecture Presentation Aqueous Equilibria: Acids and BasesWhy study acids and bases?Slide 3Slide 4Slide 5Concepts to ReviewArrhenius ConceptSlide 8The Hydrated Proton: Hydronium IonBronsted-Lowry ConceptSlide 11Slide 12Slide 13Slide 14Slide 15Slide 16Slide 17Slide 18Slide 19Slide 20Acid-Base StrengthStrong AcidsSlide 23Weak AcidsSlide 25Relative Acid-Base StrengthMore on Neutralization ReactionsAutoionization of WaterExample Problem 1 (1a and 1b on Example Problem Handout)Example Problem 2 (5a and 5b on Example Problem Handout)Problem Solving StrategypH and pOH Scales: Convenient ways to express acidity and basicitypH and pOH ScalesExample 3 (2a on Example Problem Handout)pH Calculations with CalculatorsExample 4 (3a on Example Problem Handout)Calculating [H3O+] from pHClassifying Aqueous SolutionsExample 5 (6a on Example Problem Handout)Slide 40Slide 41Example 6 (7a on Example Problem Handout)Weak Acid and Base IonizationsWeak Acid IonizationKa’s for Some Weak AcidsCalculations with KaCalculations Using KaExample 7 (8a on the Example Problem Handout)Slide 49Example 8 (Example 9a on Example Problem Handout)Weak Base IonizationExample 9 (10a on Example Problem Handout)Acid-Base Properties of SaltsSlide 54Example 10 (11a on Example Problem Handout)PowerPoint PresentationAcid-Base Properties of Salts Predicting pH of Salt SolutionsLewis ConceptSlide 59Slide 60Slide 61Lewis Acid-Base Concept Hydrolysis of Metal IonsSlide 63Slide 64Slide 65End of Presentation01/14/19 Chapter 16 1CHEM160 General Chemistry IILecture PresentationAqueous Equilibria: Acids and BasesDr. Daniel AutreyChapter 1601/14/19 Chapter 16 2Why study acids and bases? Acids and bases are common in the everyday world as well as in the lab.Some common acidic products•vinegar (dilute acetic acid), soft drinks (carbonic acid), aspirin (acetylsalicylic acid), vitamin C (ascorbic acid), lemonade (citric acid + ascorbic acid), muriatic acid (hydrochloric acid)Some common basic products•Antacids such as milk of magnesia (magnesium hydroxide) and tums (calcium carbonate), household ammonia, oven and drain cleaners (sodium hydroxide), some bleaches (sodium hydroxide)01/14/19 Chapter 16 3Why study acids and bases? Many biological and geological processes involve acid-base chemistry.Gastric juice contains hydrochloric acidLactic acid builds up in muscles during strenuous exerciseBasicity of blood must be maintained within a certain narrow range or death can resultAcidity/basicity of soil and water are of importance to animals and plants living thereCave formation and weathering of rocks is affected by acidity of water01/14/19 Chapter 16 4Why study acids and bases? 15 of the top 50 chemicals produced in the largest quantities annually in the U.S. are acids or bases. (#1 = sulfuric acid)Used as reactants and catalysts in manufacture of various consumer and industrial products•Plastics, synthetic fibers, detergents, pharmaceuticals, agricultural fertilizers, explosives, etc.01/14/19 Chapter 16 5Why study acids and bases? So why study this acid-base stuff?Acid-base reactions constitute an important class of chemical reactionsUnderstanding acid-base chemistry is necessary for chemistry, biology, geology, and other related scientific disciplines01/14/19 Chapter 16 6Concepts to ReviewAqueous Reactions and Solution StoichiometryAcids and bases, neutralization, electrolytes (section 4.3)Molarity and molarity calculations (section 4.5)Solution stoichiometry (section 4.7)Chemical equilibriumEquilibrium constants, solving equilibrium problems, LeChatelier’s principle (chapter 14)01/14/19 Chapter 16 7Arrhenius ConceptArrhenius Concept (S. Arrhenius, 1887)Acids produce hydrogen ions, H+, in water•H+ ions attach to H2O molecules forming hydronium ions, H3O+Bases produce hydroxide ions, OH-, in water•Base contains OH group in its formula.Neutralization reaction: acid + base  salt + water01/14/19 Chapter 16 8Arrhenius ConceptArrhenius Concept (S. Arrhenius, 1887)Acids produce hydrogen ions, H+, in water•H+ ions attach to H2O molecules forming hydronium ions, H3O+Bases produce hydroxide ions, OH-, in water•Base contains OH group in its formula.Neutralization reaction: acid + base  salt + water Problems•Some basic substances do not have OH-•Confined to H2O solutions•H+ does not exist free in water–Forms H3O+01/14/19 Chapter 16 9The Hydrated Proton: Hydronium Ion01/14/19 Chapter 16 10Bronsted-Lowry ConceptBronsted-Lowry Concept (J. Bronsted, T. Lowry, 1923)Acid-base reaction involves proton transfer•HA + B  HB+ + A-Acid: proton donorBase: proton acceptor •does not have to have OH- in formula01/14/19 Chapter 16 11HCl + H2O H3O+ + Cl-acid baseBronsted-Lowry ConceptExample:01/14/19 Chapter 16 12NH3 + H2O NH4++ OH-baseacidBronsted-Lowry ConceptExample:01/14/19 Chapter 16 13Bronsted-Lowry ConceptBronsted-Lowry Concept (J. Bronsted, T. Lowry, 1923)Acid-base reaction involves proton transferAcid: proton donorBase: proton acceptor •does not have to have OH- in formulaWater is amphoteric01/14/19 Chapter 16 14HCl + H2O H3O+ + Cl-acid baseBronsted-Lowry ConceptNH3 + H2O NH4++ OH-baseacid01/14/19 Chapter 16 15Bronsted-Lowry ConceptBronsted-Lowry Concept (J. Bronsted, T. Lowry, 1923)Acid-base reaction involves proton transferAcid: proton donorBase: proton acceptor •does not have to have OH- in formulaWater is amphotericAcids & bases can be molecules or ions01/14/19 Chapter 16 16Bronsted-Lowry ConceptNH4+ + H2O H3O+ + NH3baseacid01/14/19 Chapter 16 17Bronsted-Lowry ConceptBronsted-Lowry Concept (J. Bronsted, T. Lowry, 1923)Acid-base reaction involves proton transferAcid: proton donorBase: proton acceptor •does not have to have OH- in formulaWater is amphotericAcids & bases can be molecules or ionsBack reaction is also a proton transfer.01/14/19 Chapter 16 18NH3 + H2O NH4++ OH-baseacidBronsted-Lowry Conceptacidbase01/14/19 Chapter 16 19NH3 + H2O NH4++ OH-baseacidBronsted-Lowry ConceptacidbaseAcid-base conjugate pairs01/14/19 Chapter 16 20Bronsted-Lowry ConceptConjugate Acid-Base Pair (HA/A-, HB+/B)Two chemical species whose formulas differ by only one protonacid  conj. base + H+base + H+ conj. acid01/14/19 Chapter 16 21Acid-Base StrengthStrong acidsIonize completely in waterHX + H2O  H3O+ + X-Weak acidsIonize only partially in waterHX + H2O  H3O+ + X-Common weak acids: Numerous molecules and certain cations (we’ll learn