Reducing agent K Ca Half-reaction Eº (volts) K⇒ K++e -2.93 Ca Ca2++2e -2.87 Na Na Na+e -2.71 Mg Mn Mg Mg2++2e -2.36 Mn Mn2++2e- -1.18 Zn ZnZn2++2e -0.76 Fe Fe⇒ Fe²++2e- -0.47 Ni Ni⇒ Ni²++2e- -0.24 Pb PbPb2++2e -0.13 H₂ H₂ = 2H++2e 0.00 (SHE) Cu+ Cu Cu2++e +0.16 3 3 Cu Cu Cu⇒ Cu2++2e +0.34 => Cu Cu++e +0.52 Fe²+ Fe2+ Fe3++e +0.76 Ag Ag⇒ Ag++e +0.80 Hg Hg= ⇒ Hg2++2e- +0.85 CI- aub2C-> Cl₂+2e- *E°-AG In F (equation 8.22); AG calculated using AG, 298.15 Robie and Hemmingway (1995) listed in Appendix 6. = +1.36 values in