Zns 2 h aq zn2 h2g eo 076 v therefore

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Unformatted text preview: is reduction of H + by Zn metal. Zn(s) + 2 H+ (aq) --> Zn2+ + H2(g) Eo = +0.76 V Therefore, Eo for Zn ---> Zn2+ (aq) + 2e- is +0.76 V Zn +0.76 Zn is a (better) (poorer) reducing agent than H 2. (better) 7 Cu/Cu2+ and H2/H+ Cell Cu/Cu2+ and H2/H+ Cell Cu/Cu2+ and H2/H+ Cell Cu/Cu2+ and H2/H+ Cell 8 Zn/Cu Electrochemical Cell Zn/Cu Electrochemical Cell wire Volts Eo = +0.34 V Positive Cu Acceptor of electrons - Negative + 2e- --> Cu Cu2+ + 2eCu Reduction REDUCTION Cathode CATHODE Supplier of electrons H+ Overall reaction is reduction of by H2 gas. Cu2+ (aq) + H2(g) ---> Cu(s) + 2 H +(aq) Measured Eo = +0.34 V Therefore, Eo for Cu2+ + 2e- ---> Cu is H2 --> 2 + 2eH2 Oxidation + 2e2 H+ OXIDATION Anode ANODE +0.34 V 10 ele c t rons Zn2+ ions salt bridge TABLE OF STANDARD TABLE OF STANDARD REDUCTION POTENTIALS REDUCTION POTENTIALS oxidizing ability of ion wire Zn H2 2 H+ + 2eOXIDATION ANODE Cu 2+ H+ Uses of Eo Values Eo • Organize halfreactions by relative ability to act as oxidizing agents • Table 21.1 • Use this to predict cell potentials and direction of redox direction redox reactions. Anode, negative, source of electrons H+ Cu2+ + 2eCu REDUCTION CATHODE H2 Cu2+ ele c t rons Salt Bridge Cu2+ Salt Bridge Cu2+ + Zn H2 Volts + Cu Cu Cu2+ ions Cu2+ + 2e2 H+ + 2eZn2+ + 2e- Eo (V) salt bridge Zn2+ ions H2 Zn +0.34 0.00 -0.76 reducing ability of element Page 2 + Cu Cu2+ ions Cathode, positive, sink for electrons Zn(s) ---> Zn 2+(aq) + 2eEo...
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This note was uploaded on 10/19/2011 for the course CHM 2210 taught by Professor Reynolds during the Fall '01 term at University of Florida.

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