L34S10_Acid-Base-weak+04-16-10

L34S10_Acid-Base-weak+04-16-10 - Chem1A, L 34:...

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Unformatted text preview: Chem1A, L 34: "Strong and Weak Acids and Bases" Acid-Base Equilibrium, AcidConjugate A/B Ionization, Dissociation acid base acid base Previously HA + B BH + A BH acid base acid + base - HA + H2O H3O+ + A- Ka = [H30+][A-] [HA] + - HA : H3O+ HAc H2O B : OH- NH3 H2O acid A- : H2O Ac- OH- BH+ : H2O NH4+ H3O+ © A.Pines,M.Kubinec,UCB L27-4 H2 O + B base acid BH+ + OH- Kb= base [BH+][OH-] [B] L27-5 + - © A.Pines,M.Kubinec,UCB Autoionization, Autoionization, Autodissociation of H 2O acid Strong Acid-Base Titration Acid13.0 0.1 M HCl 1 Liter 13.0 7.0 1.0 0.1 M NaOH 1 Liter H2O+H20 -14 base H3O +OH acid base + Kw=1.0x10-14 at 25º C [H30+]=[OH-]=1.0x10-7M ]=[OH pX = -log[X] log[X © A.Pines,M.Kubinec,UCB Kw=[H30 ][OH ] =[H ][OH + - 7.0 1.0 E.P. E.P. Pure H2O : pH = pOH = 7.0 L27-6 0.1 mol H3O+ © A.Pines,M.Kubinec,UCB OHOH- - 0.1 mol H3 O + + ©A.Pines,M.Kubinec,UCB L34-1 L27-9 The pH Scale pX [H30+]=1.0x10-14M ]=1.0x10 [OH-]= 1.0x10-0M pH = -log[X] O+] log[H H X log[X 3 -log 14 [H30+] [H30+]=[OH-]=1.0x10-7M -log 7 [H30+]=1.0x10-0M ]=1.0x10 [OH-]= 1.0x10-14M ©A.Pines,M.Kubinec,UCB -log 0 L34-2 Strong Acid Base Titration 13.0 7.0 1.0 0.1 M HCl 1 Liter 13.0 7.0 1.0 0.1 M NaOH 1 Liter E.P. E.P. 0.1 mol H 3O + OHOH- 0.1 mol H3O+ L34-3 ©A.Pines,M.Kubinec,UCB ©A.Pines,M.Kubinec,UCB 1 Chem1A, L 34: "Strong and Weak Acids and Bases" ChemQuiz ChemQuiz 34.1 Shown is the titration curve for HCl with 0.1 M NaOH. NaOH. Which corresponds to the titration of HCl with 0.2 M NaOH? NaOH? mL A) ©A.Pines,M.Kubinec,UCB B) C) L34-4 Weak Acid/Base (HAc/Ac -) (HAc/Ac acid Weak Base/Acid (NH 3/NH 4+) NH3 + H2O base acid base HAc + H2O Summary + - base acid H3O+ + Ac - Ka = 1.8x10-5 1.8x10 pKa = 4.7 4.7 base base OH- + NH4+ Kb = 1.8x10-5 1.8x10 pKb = 4.7 4.7 base acid - acid + acid H2O + Ac- base acid HAc + OH - Kb = 5.6x10-10 5.6x10 pKb = 9.3 9.3 L36-4 - H2O + NH4+ base acid NH3 + H3O+ Ka = 5.6x10-10 5.6x10 pKa = 9.3 9.3 L36-5 + ©A.Pines,M.Kubinec,UCB ©A.Pines,M.Kubinec,UCB Conjugate Acid/Base Pair HAc+H2O HAc+H Ka = + H3O ++Ac- + - H2O +Ac- HAc +OH- [H30 ][Ac ] [HAc] HAc] X Kb = [HAc][OH-] HAc][OH [Ac-] Ka Kb = [H30+][OH-] = Kw ©A.Pines,M.Kubinec,UCB L28-7 Weak Acid/Base (HAc/Ac-) acid HAc + H2O base acid H3O + Ac + base - Ka = 1.8x10-5 1.8x10 pKa = 4.7 4.7 acid base acid base H2 O + Ac- HAc + OH- Kb = 5.6x10-10 5.6x10 pKb = 9.3 9.3 L34-7 ©A.Pines,M.Kubinec,UCB ©A.Pines,M.Kubinec,UCB 2 Chem1A, L 34: "Strong and Weak Acids and Bases" Weak Base/Acid (NH3/NH4+) NH3 + H2O base acid base OH + NH4 Kb = 1.8x10-5 1.8x10 pKb = 4.7 4.7 - acid + H2O + NH4+ base acid NH3 + H3O Ka = 5.6x10-10 5.6x10 pKa = 9.3 9.3 L34-8 base acid + ©A.Pines,M.Kubinec,UCB ChemQuiz© 34.2 Which of the following 0.1 M solutions has the highest highest pH ? A) NaAc ©A.Pines,M.Kubinec,UCB B) NH3 C) NH4Cl L34-9 Conjugate Acid/Base Pair HAc+H2O Ka = + H3O +Ac - + - H2O +Ac- HAc +OH - [H30 ][Ac ] [HAc] X Kb = [HAc][OH-] [Ac-] Ka Kb = [H30+][OH-] = Kw ©A.Pines,M.Kubinec,UCB L34-11 ©A.Pines,M.Kubinec,UCB 3 Chem1A, L 34: "Strong and Weak Acids and Bases" Conjugate Base/Acid Pair NH3+H2O Kb = NH NH4++OH- H2O +NH4+ NH3 +H3O+ [NH4+][OH-] [NH3] X Ka = [H30+][NH3] [NH4+] Kb Ka = [H30+][OH-] = Kw ©A.Pines,M.Kubinec,UCB L34-12 ChemQuiz© 34.3 For the Acids HA1 and HA2, pKa1 < pKa2. Which is true for tru HA1 + A2 A) K < 1 ©A.Pines,M.Kubinec,UCB HA1 HA2 - HA2 + B) K = 1 A1C) K > 1 L34-13 ChemQuiz© 34.4 For the Acids HA1 and HA2, pKa1 < pKa2. Which is true for tru HA1 + A2 - HA1 HA2 HA2 + A1- A) K = Ka1+Ka2 B) K = Ka1Ka2 C) K =Ka1/Ka2 ©A.Pines,M.Kubinec,UCB L34-15 ©A.Pines,M.Kubinec,UCB 4 Chem1A, L 34: "Strong and Weak Acids and Bases" Lecture Complete ©A.Pines,M.Kubinec,UCB L34-17 ©A.Pines,M.Kubinec,UCB 5 ...
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This note was uploaded on 04/24/2010 for the course CHEM 1A taught by Professor Nitsche during the Spring '08 term at University of California, Berkeley.

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