CHEM 1120 1st Edition Lecture 13 Outline of Last Lecture I. Acid-Base Reactionsa. Autoionization of waterb. pH equationc. Acid disassociation constantII. Strong Acids and Basesa. Strong acidsb. Strong basesc. Weak acidsOutline of Current Lecture I. Equilibrium calculationsa. Percent ionizationb. Stepwise methodII. Weak bases and their relation to weak acidsa. Kb = [conjugate acid][OH-]/[base]b. Categories of weak basesIII. Relationship between Ka and Kba. Kw = Ka x KbIV. Acid Base properties of Salt solutionsV. Acid Base behavior and chemical structurea. 3 factorsCurrent LectureI. Equilibrium calculationsa. K = x^2 / concentration-xb. Percent ionization (HX dissociated/HX initial) x 100These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.c. For weak acidsi. High H+ concentrationsii. Lower percent ionizationsd. Stepwise method suitable when Ka1 >> Ka2, II. Weak bases and their relation to weak acidsa. Strong bases are strong electrolytesb. Weak bases are weak electrolytesc. Base + water conjugate acid + OH-d. Kb = [conjugate acid][OH-]/[base]i. Water is omittedii. Smaller Kb = weaker baseiii. For all strong bases, Kb >>> 1e. 2 categories of weak basesi. Neutral molecules with lone pairs of electronsii. Conjugate bases of weak acids (Charged)III. Relationship between Ka and Kba. Ka = [H+][X-]/[HX]b. Kb = [HX][OH-]/[X-]c. Ka x Kb = Kwd. Kw at 25 degrees C = 1x10^-14e. Pkw = pKa + pKb = 14IV. Acid base properties of salt solutionsa. Often speak of “Acids, bases, and salts”-suggesting that salts are neutral. Not true!b. Acidic salts: have NH4-ammoniumc. Basic salts: NaCN, KFd. Neutral salts: NaBr, KCle. How do we predict? Decide if and how its ions react with waterf. Conjugate base of a strong acid and cation of a strong base will not hydrolyzeg. Conjugate base of a weak acid and conjugate acid of a weak base will hydrolyzeh. What happens if both parents of a salt are weak? Look at Kb and KaV. Acid base behavior and chemical structurea. Predicting acid strength is not easyb. 3 major factorsi. H-X bond polarity: More positive H a more acidic Hii. H-X bond strength: weaker H-X bond a more acidic Hiii. Conjugate base stability: more stable X- more acidic Hc. Trendsi. Down and right: stronger acidsii. Up and left: stronger basesd. Compare conjugate acidse. Factors affecting acid strengthi. In oxyacids in which an OH is bonded to another atom, the more electronegative the atom is, the more acidic the
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