L34S09_Acid-Base_strong-weak+04-17-09

L34S09_Acid-Base_strong-weak+04-17-09 - 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 Previously HA + B BH + A BH acid base acid + base - HA + H2O H3O+ + A- base 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 H2O 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 The pX Scale [H30+]=1.0x10-14M ]=1.0x10 [OH-]= 1.0x10-0M log[H H pH = -log[X] O+] X log[X 3 -log 14 [H30+] [H30+]=[OH-]=1.0x10-7M ]=[OH ]=1.0x10 -log 7 [H30+]=1.0x10-0M ]=1.0x10 [OH-]= 1.0x10-14M ©A.Pines,M.Kubinec,UCB -log 0 L34-2 ChemQuiz© 33.2 x 10-14 Shown is Kw for H2O versus temperature. What is the pH of hot water? water? 10.0 1.0 25ºC 25º 60ºC 60º A) = 7.0 ©A.Pines,M.Kubinec,UCB B) < 7.0 C) > 7.0 L34-3 ©A.Pines,M.Kubinec,UCB 1 Chem1A, L 34: "Strong and Weak Acids and Bases" 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 H3O + OHOH- 0.1 mol H3O+ L34-5 ©A.Pines,M.Kubinec,UCB ChemQuiz 34.1 Shown is the titration curve for HCl with 0.1 M NaOH. Which corresponds NaOH. to the titration of HCl with 0.2 M NaOH? NaOH? mL A) ©A.Pines,M.Kubinec,UCB B) C) L34-6 Weak Acid/Base (HAc/Ac-) (HAc/Ac acid Weak Base/Acid (NH3/NH4+) 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 ©A.Pines,M.Kubinec,UCB 2 Chem1A, L 34: "Strong and Weak Acids and Bases" Weak Acid/Base (HAc/Ac-) HAc + H2O acid base acid H3O + Ac- Ka = 1.8x10-5 1.8x10 pKa = 4.7 4.7 base - + base - acid H2O + base Ac- acid HAc + OH- Kb = 5.6x10-10 5.6x10 pKb = 9.3 9.3 L34-9 ©A.Pines,M.Kubinec,UCB Weak Base/Acid (NH3/NH4+) NH3 + H2O base acid base OH- + NH4+ Kb = 1.8x10-5 1.8x10 pKb = 4.7 4.7 base acid - acid + H2O + base acid NH4+ NH3 + H3O+ Ka = 5.6x10-10 5.6x10 pKa = 9.3 9.3 L34-10 + ©A.Pines,M.Kubinec,UCB ChemQuiz© 34.3 Which of the following 0.1 M solutions has the highest pH ? A) NaAc ©A.Pines,M.Kubinec,UCB B) NH3 C) NH4Cl L34-11 ©A.Pines,M.Kubinec,UCB 3 Chem1A, L 34: "Strong and Weak Acids and Bases" Conjugate Acid/Base Pair HAc+H2O H3O++Ac+ - H2O +Ac- HAc +OH- [H30+][Ac-] Ka = [HAc] HAc] X Kb = [HAc][OH-] [Ac-] Ka Kb = [H30+][OH-] = Kw ©A.Pines,M.Kubinec,UCB L34-13 Conjugate Base/Acid Pair NH3+H2O Kb = + NH4 +OH- H2O +NH4+ NH3 +H3O+ NH [NH4+][OH-] X [NH3] Ka = [H30+][NH3] [NH4+] Kb Ka = [H30+][OH-] = Kw ©A.Pines,M.Kubinec,UCB L34-14 ChemQuiz© 34.4 For the Acids HA1 and HA2, pKa1 < pKa2. Which is true for HA1 + A) K < 1 ©A.Pines,M.Kubinec,UCB HA1 HA2 A2- HA2 + B) K = 1 A1C) K > 1 L34-15 ©A.Pines,M.Kubinec,UCB 4 Chem1A, L 34: "Strong and Weak Acids and Bases" ChemQuiz© 34.5 For the Acids HA1 and HA2, pKa1 < pKa2. Which is true for HA1 + A2HA2 + A1- HA1 HA2 A) K = Ka1+Ka2 B) K = Ka1Ka2 C) K =Ka1/Ka2 ©A.Pines,M.Kubinec,UCB L34-17 Lecture Complete ©A.Pines,M.Kubinec,UCB L34-19 ©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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