CHEM 1120 Edition 1nd Exam 2 Study Guide Chapters 16 and 17 Chapter 16 Arrhenius acid Substance that directly yields H ions when dissolved in H2O Ex HCl Cl H Arrhenius Base Substance that directly yields OH ions when dissolved in H2O Ex NaOH Na OH Bronsted Lowery Acid Donates a H Bronsted Lowery Base Accepts an H Brontsted Lowry Example NH3 base H20 acid NH4 acid OH base Conjugate acid base pair 2 species whose formulas differ by a single H Ex HCN CN Acid base strength H2O H30 Strong acid strong electrolytes disassociates 100 Stronger acid weaker conjugate base Stronger base weaker conjugate acid Common strong acids HCl HclO3 HNO3 HBr HClO4 H2SO4 HI Common strong bases Hydroxides of Group 1A metals LiOH NaOH KOH Heavy group 2A metals Ca OH 2 Ba OH 2 Sr OH 2 Kw H OH 1 0x10 14 25 degrees Celsius pH log10 H 10 ph H pKw pH pOH 14 Sig figs note 2 sig figs in log 2 significant decimal places Ka H A HA Acid dissociation contant K 1 strong acid Kb 1 weak acid H30 acid For monoprotic strong acids Percent ionization HX dissociated HX initial x 100 Polyprotic acids 2 Ka s work step wise Kb HX OH X Kw Ka x Kb pKa pKb 14 Hydrolysis Determining if salt is acidic or basic Predicting acid strength Reaction of ions with water to produce H or OH ions conjugate base of weak acid and vice versa will hydrolyze 1 Identify ions formed in aqueous solution 2 Assume cation and anion react with water 3 Are either or both of these reactions unrealistic H X bond polarity and strength conjugate base stability More oxygens more acidic Lewis acid Electron pair acceptor Lewis base Electron pair donor Chapter 17 Common ion Ion common to 2 solutes shift in equilibrium caused by the addition of an ion already present in solution Buffers Resist pH change when small amounts of acid or base is added Buffer composition Weak acid conjugate base or weak base conjugate acid pH pKa log base acid Henderson Hasselbach equation Choosing acid base pair Buffer capacity 1 Choose acid with pKa closest to desired pH 2 Solve Henderson Hasselbach equation for base acid ratio Amount of acid or base a buffer can neutralize before pH changes significantly more concentration buffers have higher capacity capacity highest when concentrations of conjugates are equal Titration Accurate measurement of volume of solution required to completely react with a sample Equivalence point Point at which stoichiometrically equivalent quantities of reactant are brought together End point Point at which indicator changes color very near equivalence point Calculating solubility equilibria Use ICE table molecule is dissociating Ksp C c D d Solubility product Factors affecting solubility Common ion effect pH complex ion formation amphotorism Amphotorism Will react in both acids and bases
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