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Acid/Base Arrhenius definition acid produces H+ in water base produces OH- in water HA + H2O H+ + A- Ka = [H+] [A-] Ka strength of acid [HA] [H2O] [HA] strong acids no Ka weak acids dissociate completely equilibrium process HCl, HBr, HI HF Ka = 6.8 x 10-4 HNO3, HClO4, H2SO4 HIO3 Ka = 0.16
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Acid/Base Arrhenius definition acid produces H+ in water base produces OH- in water NaOH (s) + H2O Na+(aq) + OH- (aq) NH3 (g) + H2O NH4+ (aq) + OH- (aq) strong bases weak bases Kb OH- Group I NH3 Kb = 1.8 x 10-5 Group II O2- R-NH2 amines (Ca, Sr, Ba)
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Brønsted-Lowry Acids and Bases
proton donor H .. base proton acceptor O H .. .. O H + H Cl + Cl- + conjugate pair base acid strong acid very weak base conjugate pair stronger acid stronger base +
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Brønsted-Lowry Acids and Bases
strength of acid related to stability of conjugate base conjugate bases carry negative charges stabilized by: polarizability related to size (LDF) electronegativity inductive effect resonance e- in HI H+ + I- 5p orbital largest orbital most stable HBr H+ + Br- 4p orbital HCl H+ + Cl- 3p orbital strongest acid HF H+ + F- 2p orbital
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Brønsted-Lowry Acids and Bases
strength of acid related to stability of conjugate base conjugate bases carry negative charges stabilized by: electronegativity with same size orbitals, electronegativity determines stability F- OH- NH2- CH3- HF > H2O > NH3 > CH4
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Brønsted-Lowry Acids and Bases
strength of acid related to stability of conjugate base conjugate bases carry negative charges inductive effect related to electronegativity – but atom near charge more stable base stronger acid
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Brønsted-Lowry Acids and Bases
strength of acid related to stability of conjugate base conjugate bases carry negative charges resonance HNO3 HNO2 For oxoacids with same central atom, more O means stronger acid For oxoacids with same number of O, more electronegative central atom means stronger acid
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Brønsted-Lowry Acids and Bases
proton donor base proton acceptor N H + N H .. O H .. .. O H - + + acid base base acid weak base relatively strong acid Kb = 1.8 x 10-5
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Autoionization of H2O H H2O H+ (aq) > + OH- (aq) Kw = [H+] [OH-] = 1.0 x 10-14 at 25oC [H+] [H2O] = [OH-] 55.5 M = 1.0 x 10-7 Kw = [0.1] [OH-] = 1.0 x 10-14 [OH-] = 1.0 x 10-13 Le Chatelier add H+ [OH-] decrease 0.10 mol HCl = 0.1 mol H+ [H+] = 0.10 M 1.0 L L both present in all aqueous solutions
![Autoionization of H2O H. H2O. H+ (aq) > + OH- (aq) Kw = [H+] [OH-] = 1.0 x at 25oC.](http://slideplayer.com./slide/14140657/86/images/9/Autoionization+of+H2O+%EF%81%84H.+H2O.+%EF%81%84+H%2B+%28aq%29+%3E+%2B+OH-+%28aq%29+Kw+%3D+%5BH%2B%5D+%5BOH-%5D+%3D+1.0+x+at+25oC..jpg "[H+] [H2O] = [OH-] 55.5 M. = 1.0 x Kw = [0.1] [OH-] = 1.0 x [OH-] = 1.0 x Le Chatelier. add H+ [OH-] decrease mol HCl. = 0.1 mol H+ [H+] = 0.10 M. 1.0 L. L. both present in all aqueous solutions.")
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pH [H+] 10 M M pH = - log [H+] low pH -1 15 high pH acidic basic neutral [H+] = [OH-] = 1.0 x 10-7 pH = 7 pOH = - log [OH-] pH + pOH = 14 pH of milk = 6.4 [H+] = x 10-7 -6.4 10 4 x 10-7 1 sig. fig.
![pH [H+] 10 M M. pH = - log. [H+] low. pH high pH. acidic. basic. neutral.](http://slideplayer.com./slide/14140657/86/images/10/pH+%5BH%2B%5D+10+M+M.+pH+%3D+-+log.+%5BH%2B%5D+low.+pH+high+pH.+acidic.+basic.+neutral..jpg "[H+] = [OH-] = 1.0 x pH = 7. pOH = - log. [OH-] pH. + pOH. = 14. pH. of milk. = 6.4. [H+] = x x sig. fig.")
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Brønsted-Lowry Acids and Bases
proton donor base proton acceptor C2H3OOH + CN- C2H3OO- + HCN acid base base1 acid2 1 2
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Brønsted-Lowry Acids and Bases
proton donor base proton acceptor HF + H2O Ka = 7.2 x 10-4 F- + H3O+ acid1 base2 base1 acid2 CH3NH2 + H2O CH3NH3+ + OH- base1 acid2 acid1 base2 H3O+ strongest acid in water H2O amphoteric OH- strongest base in water acid or base
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![Acid/Base Arrhenius definition acid produces H + in water baseproduces OH - in water HA K a = [H + ] [A - ] [HA] [H 2 O] KaKa strength of acid strong acids.](/32/9996692/big_thumb.jpg "Acid/Base Arrhenius definition acid produces H + in water baseproduces OH - in water HA K a = [H + ] [A - ] [HA] [H 2 O] KaKa strength of acid strong acids.>")
