L37S07_Polyprotic Acids, Amino Acids 04-20-07

L37S07_Polyprotic Acids, Amino Acids 04-20-07 - Chem 1A L...

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Unformatted text preview: Chem 1A L 37: "Polyprotic Acids, Amino Acids " pH Titration of a Weak Acid by a Strong Base D C B AE.P. A HA Summary TITRATION O + Ac HAc + H O H WEAK-ACID BASE OH0.1 - x 2 Region A : 0.1 M HAc 3 + - x x Expect: 1.0 < pH < 7.0 HA/AHA/ Buffer acid HA + OH- base H2O + A- acid base Assume 0.1-x ? 0.1 0.1x2 = Ka = 1.76 x 10-5 0.1- x pH = 2.88 0.1x2 = 0.1 Ka x = 1.33x10-3 L29-6 + OHA.Pines,M.Kubinec,UCB L29-4 A.Pines,M.Kubinec,UCB Region C : 0.1 M AcAc - + H2O 0.1 - x Region B : [HA] ~ [HA] pH Buffer [A-] HAc +OHx Expect: x 7.0 < pH < 13.0 x2 = Kb = 5.68 x 10-10 0.1- x 0.1x2 = 0.1 Kb A.Pines,M.Kubinec,UCB Assume 0.1-x ? 0.1 0.1pH = 8.88 [HA] = [A-] x = 7.5x10-6 L29-8 A.Pines,M.Kubinec,UCB E.P. A.Pines,M.Kubinec,UBC HA + OH- H2O + AH2O + HA A- + H3O+ K >> 1 + L37-1 OHL30-4 ChemQuiz 36.2 Shown in yellow is the titration of HNO3 per mole KOH. Which is KOH. the correct curve for x10 dilution of HNO3? 1) A.Pines,M.Kubinec,UCB H2O HNO3 2) mol OHmol OH- 3) mol OHL37-2 ChemQuiz 36.3 Shown is in yellow the titration of HAc per mole KOH. Which is the KOH. correct curve for x10 dilution of HAc? HAc? 1) A.Pines,M.Kubinec,UCB H2O HAc 2) mol OHmol OH- 3) mol OHL37-4 A.Pines,M.Kubinec,UCB 1 Chem 1A L 37: "Polyprotic Acids, Amino Acids " PolyProtic Acids/Blood Buffer Summary Blood pH Stats: pH PCO = 40 torr 2 pKa2 pKa1 +OH A.Pines,M.Kubinec,UBC [CO2] = 1.2 mM [CO2] = [H2CO3] Carbonic Anhydrase Kidneys Lungs Henry's Law [HCO3-] = 24 mM L30-12 A.Pines,M.Kubinec,UCB L37-6 PolyProtic Acids: Indicators Thymol Blue (H2Thy) (H Thy) HThypH pKa2 Thy-2 + H+ pKa2 = 8.8 pKa1 H2Thy HThy- + H+ +OH- pKa1 = 2.0 A.Pines,M.Kubinec,UCB L37-7 PolyProtic Acids H2CO3 pH H3PO4 H2SO4 trend: pKa1 < pKa2 < pKa3 pKa2 pKa1 HCO3H2CO3 +OH- CO3-2 + H3O+ pKa2 = 10.2 HCO3- + H3O+ pKa1 = 6.1 A.Pines,M.Kubinec,UCB L37-8 A.Pines,M.Kubinec,UCB 2 Chem 1A L 37: "Polyprotic Acids, Amino Acids " ChemQuiz 37.1 Which carbonate species is present in the highest concentration at pH 7 ? pKa2 pKa1 1) H2CO3 A.Pines,M.Kubinec,UCB 2) HCO3 -1 3) CO3 -2 L37-9 PolyProtic Acids/Blood Buffer Blood pH Stats: pH PCO = 40 torr 2 pKa2 pKa1 +OHA.Pines,M.Kubinec,UCB [CO2] = 1.2 mM [CO2] = [H2CO3] Carbonic Anhydrase Kidneys Lungs Henry's Law Henry' [HCO3-] = 24 mM L37-11 PolyProtic Acids/Blood Buffer Blood pH Stats: Henry's Law Henry' 24] [[24] 3-] HCO pH = pKa + log 6.1 [H2CO3] [CO2] = 1.2 mM [1.2] 1.2] [CO2] = [H2CO3] [H Carbonic Anhydrase pH = 7.4 [HCO3-] = 24 mM Kidneys PCO = 40 torr 2 Lungs A.Pines,M.Kubinec,UCB L37-12 A.Pines,M.Kubinec,UCB 3 Chem 1A L 37: "Polyprotic Acids, Amino Acids " 9.0 Amino Acid pKa's C C C C +N -O O C C + N 9.1 pH = 7.0 10.5 10.1 C C C C C C O 2.2 Lysine O +N 2.2 C C C - O Tyrosine A.Pines,M.Kubinec,UCB L37-13 Amino Acid pKa's +N 2.0 O 10 O C C C 3.9 O 9.2 N N C C C C pH = 7.0 C O - Aspartic Acid O O + C N N C C C N N 6.0 C C A.Pines,M.Kubinec,UCB 1.8 O O Histidine L37-14 ChemQuiz 37.2 Solution pKa: pKa= 9.0 pH < pKa: acid form pH 5.0 - N + + C O C C S pH < pKa: acid form pKa: pKa= 8.0 pH > pKa: base form pKa: pKa= 2.2 1) + 1 A.Pines,M.Kubinec,UCB 2) 0 3) -1 L37-16 A.Pines,M.Kubinec,UCB 4 Chem 1A L 37: "Polyprotic Acids, Amino Acids " Lecture complete A.Pines,M.Kubinec,UCB L37-17 A.Pines,M.Kubinec,UCB 5 ...
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This note was uploaded on 08/19/2009 for the course CHEM 1A taught by Professor Nitsche during the Spring '08 term at Berkeley.

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