§76 Reversible cell 7. 6. 4 Reversible electrodes Important reduction-oxidation electrode 3)The third-type electrode: oxidation-reduction(redox)electrodes: Pt(s)I Fe(CN3(c), Fe(CN)-(c) immersion of an inert metal current collector(usually Pt)in a solution which Fe(CN)63(c1)+e-—>Fe(CN64(c2) contains two ions or molecules with the same composition but different states of Pt(s)lQ, H,Q: quinhydrone electrode oxidation O Sn Pt(s)ISn4*(c1), Sn+(c2) OH n Snt Q=quinone H,Q= hydroquinone S Sn4(c1)+2e-→Sn2+(c2) S S Q+2H++2e-—>H2Q3) The third-type electrode: oxidation-reduction (redox) electrodes: immersion of an inert metal current collector (usually Pt) in a solution which contains two ions or molecules with the same composition but different states of oxidation. Pt(s)Sn4+(c1 ), Sn2+(c2 ) Sn4+(c1 ) + 2e− → Sn2+(c2 ) Pt(s)Fe(CN)6 3− (c1 ), Fe(CN)6 4− (c2 ) : Pt(s)Q, H2Q: quinhydrone electrode Fe(CN)6 3− (c1 ) + e− ⎯→ Fe(CN)6 4− (c2 ) Q + 2H + + 2e− ⎯→ H2Q Q = quinone H2Q = hydroquinone O O 2e - 2H + OH OH + + Important reduction-oxidation electrode 7.6.4 Reversible electrodes §7.6 Reversible cell