Electrochemistry

 24) (a) H₂(g) + F₂(g) 2H⁺(aq) + 2F ^-(aq)

                     H₂(g) 2H⁺(aq) + 2e^-             E°_red = 0.00 V      

             F₂(g) + 2e^- 2F ^-(aq)                       E°_red = 2.87 V
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          H₂(g) + F₂(g) 2H⁺(aq) + 2F ^-(aq)     E° = 2.87 V

          E° = E°_red(reduction) - E°_red(oxidation) = 2.87 V - 0.00 V = 2.87 V

       (b) Cu(s) + Ba²⁺(aq) Cu²⁺(aq) + Ba(s)

                             Cu(s) Cu²⁺(aq) + 2e^-          E°_red = 0.337 V      

             Ba²⁺(aq) + 2e^- Ba(s)                         E°_red = -2.90  V
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          Cu(s) + Ba²⁺(aq) Cu²⁺(aq) + Ba(s)     E° = -3.24 V

          E° = E°_red(reduction) - E°_red(oxidation) = -2.90 V - 0.337 V = -3.24 V

       (c) 3Fe²⁺(aq) Fe(s) + 2Fe³⁺(aq)

              Fe²⁺(aq) + 2e^- Fe(s)                        E°_red = -0.440 V      

                     2Fe²⁺(aq) 2Fe³⁺(aq) + 2e         E°_red = 0.771  V
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                      3Fe²⁺(aq) Fe(s) + 2Fe³⁺(aq)    E° = -1.211 V

          E° = E°_red(reduction) - E°_red(oxidation) = -0.440 V - 0.771 V = -1.211 V

       (d) Hg₂²⁺(aq) + 2Cu⁺(aq) 2Hg(l) + 2Cu²⁺(aq)

                    Hg₂²⁺(aq) + 2e^- 2Hg(l)                          E°_red = 0.789 V      

                              2Cu⁺(aq) 2Cu²⁺(aq) + 2e            E°_red = 0.153 V
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          Hg₂²⁺(aq) + 2Cu⁺(aq) 2Hg(l) + 2Cu²⁺(aq)     E° = 0.636 V

          E° = E°_red(reduction) - E°_red(oxidation) = 0.789 V - 0.153 V = 0.636 V