2014_L6_AcidsandBases

Compare pkas of the two acids reacmon will go from low

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Unformatted text preview: ll or negaDve posiDve DissociaMon far to the right far to the leF Eq m [OH ­ [OH ­ ~ [B]o [OH ­ << [B]o HB+ much weaker acid than water HB+ much stronger acid than water Strength of conjugate acid CHM1321 Acids & Bases 17 HCl (aq) + H2O (l) acid base H3O+ (aq) + Cl ­ (aq) conjugate conjugate base acid In general: A strong acid will have a weak conjugate base A strong base will have a weak conjugate acid CHM1321 Acids & Bases 18 CHM1321 Acids & Bases 19 In an acid–base reaction, the favoured direction of the reaction is from the stronger to the weaker member of a conjugate pair 1.  compare pKa’s of the two acids: –  reacMon will go from low pKa high pKa 2.  no pKa’s? compare conjugate bases –  5 criteria CHM1321 Acids & Bases 20 Compound pKa Compound pKa Compound pKa Compound pKa HClO4 -10 RCOOH 5 RCH2OH 16 HNO3 -1.4 HI -10 H2CO3 6.4 R2CHOH 17 CF3COOH 0.18 H2SO4 -10 H 2S 7 R3COH 17 HSO4 -10 PhSH 7 17 HF H O O HBr NH2 O 9 H R O -9 H H3C CH3 3.2 NH3 19.2 O HCl -7 HCN 9.2 -6.5 NH4 + 9.2 -6 PhOH -3.5 H R C NO2 H -2 HCO3 -1.7 CH3NH3 50 CH 4 OSO2H O R R R H O H 3O CH3 20 RNH3 24 RO CH3 RSH O 10 RCH2CN 11 - 10 R H 11 O 25 OR H R + 4 O H 11 H 25 CH3OH 15.2 10.2 H2 35 H 2O 15.7 10.6 NH3 38 C 6H 6 43 48 PhCH3 40 CH2=CH2 44 H + CH3CH3 CHM1321 R R H O 2 O H R - + Acids & Bases 21 Predict the products and preferred direcMon of change for the following acid ­base reacMons (is K > or < 1?) 1. CH3CO2H + H2O 2.  H2SO4 + F– 3.  HCO3– + HSO4– CHM1321 Acids & Bases 22 HCN + HS– CN– + H2S A.  Towards reactants B.  Towards products C.  I don’t know CHM1321 Acids & Bases 23 A.  Towards reactants B.  Towards products C.  I don’t know CHM1321 Acids & Bases 24 •  Consider the following extreme case: H2SO4 + HNO3 {H2NO2}+ + HSO4 ­ acid base CHM1321 conj. acid conj. base Acids & Bases 25 •  the stability of the corresponding conjugate base •  5 criteria: 1.  2.  3.  4.  5.  CHM1321 size electronegaMvity resonance inducMv...
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This note was uploaded on 03/12/2014 for the course CHM 1321 taught by Professor Flynn during the Spring '08 term at University of Ottawa.

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