L38S07_RedoxCellPot 04-23-07

L38S07_RedoxCellPot 04-23-07 - Chem 1A, L 38:...

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Unformatted text preview: Chem 1A, L 38: "Reduction Potentials" PolyProtic Acids/Blood Buffer Blood pH Stats: Summary 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 L38-1 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 L38-2 ChemQuiz 37.2 pKa= 9.0 What is the total effective charge on the amino acid cysteine at pH 5.0 ? N + C O C C S pKa= 8.0 pKa= 2.2 Cysteine 1) + 1 A.Pines,M.Kubinec,UCB 2) 0 3) -1 L38-3 A.Pines,M.Kubinec,UCB 1 Chem 1A, L 38: "Reduction Potentials" Redox and Electrochemistry Cu2+ (aq) + Zn (s) aq) oxidizer reducer Standard Galvanic Cell Cu2+ (aq) + Zn (s) aq) Summary oxidizer ? Zn2+ (aq) + Cu (s) aq) Zn2+ (aq) + Cu (s) aq) reducer ? Anode - e- Salt Bridge e- + Cathode Zn2+ 1.0 M Oxidation Zn Zn2+ + 2 e- Cu2+ 1.0 M Cu Reduction Spontaneous: G? < 0, K > 1 Zn Zn2+ + 2 eCu2+ + 2 eReduction Cu L39-4 Cu2+ + 2 e- Notation: Zn Zn2+ (1.0 M) Cu2+ (1.0 M) Cu Oxidation A.Pines,M.Kubinec,UCB = 1.10 V A.Pines,M.Kubinec,UCB L39-5 Standard Reduction Potentials = Cu Zn = (right) (left) Standard Half-Cell Potentials HalfCu2+ + 2 e2 H+ + 2 eZn2+ + 2 eCu H2 Zn = +0.34 V +0.34 1.00 atm SHE: 2 H + 2 + + + Oxidizer H2 (g) Pt (V) eH2 (g) 0.00 Reducer = +0.00 V +0.00 - Pt H2 H Cu2+ Cu + +0.34 + H+ 1.0 M A.Pines,M.Kubinec,UCB A.Pines,M.Kubinec,UCB + Pt H2 H+ Zn2+ Zn - -0.76 L39-5 A.Pines,M.Kubinec,UCB = -0.76 V L38-5 L39-3 LEO goes GER A.Pines,M.Kubinec,UCB L38-6 Loss of Electrons is Oxidation goes Gain of Electrons is Reduction A.Pines,M.Kubinec,UCB L38-7 A.Pines,M.Kubinec,UCB 2 Chem 1A, L 38: "Reduction Potentials" Redox and Electrochemistry Cu2+ (aq) + Zn (s) aq) oxidizer ? Zn2+ (aq) + Cu (s) aq) Zn2+ (aq) + Cu (s) aq) oxidizer reducer ? Cu2+ (aq) + Zn (s) aq) reducer Spontaneous: G < 0, K > 1 Zn Zn2+ + 2 eCu2+ + 2 eReduction Cu L38-8 Oxidation A.Pines,M.Kubinec,UCB OIL RIG A.Pines,M.Kubinec,UCB L38-9 Oxidation Reduction Is Is Loss Gain of electrons A.Pines,M.Kubinec,UCB L38-10 A.Pines,M.Kubinec,UCB 3 Chem 1A, L 38: "Reduction Potentials" Standard Galvanic Cell Anode - e- Salt Bridge e- + Cathode 1.0 M Oxidation Zn Zn2+ + 2 e- Zn2+ Cu2+ 1.0 M Cu Reduction Cu2+ + 2 e- Notation: Zn Zn2+ (1.0 M) Cu2+ (1.0 M) Cu = 1.10 V A.Pines,M.Kubinec,UCB L38-11 Red Cat Reduction is Cathode L38-12 A.Pines,M.Kubinec,UCB Standard Reduction Potentials = Cu Zn = (right) (left) H2 (g) 1.00 atm Pt SHE: 2 H+ + 2 e+ H+ + (V) H2 (g) 0.00 - Pt H2 H Cu2+ Cu + +0.34 1.0 M + Pt H2 H+ Zn2+ Zn - -0.76 L38-13 + A.Pines,M.Kubinec,UCB A.Pines,M.Kubinec,UCB 4 Chem 1A, L 38: "Reduction Potentials" ChemQuiz 38.1 What forms when Cu is placed in H2SO4? H2SO4 1.0 M 1) Cu2+ A.Pines,M.Kubinec,UCB 2) H2 3)nothing 3)nothing L38-14 ChemQuiz 38.2 What forms when Zn is placed in H2SO4? H2SO4 1.0 M 1) Zn2+ A.Pines,M.Kubinec,UCB 2) H2 3)nothing 3)nothing L38-16 Standard Reduction Potentials Cu2+ + 2 e2 H+ + 2 eZn2+ + 2 eCu H2 Zn = +0.34 V +0.34 = +0.00 V +0.00 = -0.76 V Reducer Oxidizer A.Pines,M.Kubinec,UCB L38-18 A.Pines,M.Kubinec,UCB 5 Chem 1A, L 38: "Reduction Potentials" ChemQuiz 38.3 Which of the following will oxidize H2? H2 (g) Pt 1.00 atm Which of the following will be reduced by H2? 1) Cu2+ A.Pines,M.Kubinec,UCB H+ 1.0 M 2) Cu 3)Zn2+ 3)Zn L38-19 ChemQuiz 38.4 When current is allowed to flow, the darker blue solution will become Cu2+ 0.1 M Cu2+ 1.0 M Cu Cu2+ (0.1M) Cu2+ (1.0M) Cu 1) Bluer A.Pines,M.Kubinec,UCB 2) Same 3)Lighter 3)Lighter L38-21 ChemQuiz 38.5 (standard) for the cell is Cu2+ 1.0 M Cu2+ 1.0 M Cu Cu2+ (1.0M) Cu2+ (1.0M) Cu 1) < 0 A.Pines,M.Kubinec,UCB 2) = 0 3)> 0 3)> L38-23 A.Pines,M.Kubinec,UCB 6 Chem 1A, L 38: "Reduction Potentials" ChemQuiz 38.6 (non-standard) (nonfor the cell is Cu2+ 0.1 M Cu2+ 1.0 M Cu Cu2+ (0.1M) Cu2+ (1.0M) Cu 1) < 0 A.Pines,M.Kubinec,UCB 2) = 0 3)> 0 3)> L38-25 Lecture Complete A.Pines,M.Kubinec,UCB L38-27 A.Pines,M.Kubinec,UCB 7 ...
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