Sulfur electrode potential diagrams

As in the corresponding discussion for the halogens (Section 22-3), oxidation-reduction chemistry is a primary concern here. To assist in this discussion, we provide electrode potential diagrams for some important sulfur-containing species in Figure 22-13. 

In the lead-acid battery, sulfuric acid has to be considered as an additional component of the charge-discharge reactions. Its equilibrium constant influences the solubility of Pb2+ and so the potential of the positive and negative electrodes. Furthermore, basic sulfates exist as intermediate products in the pH range where Fig. 1 shows only PbO (cf. corresponding Pour-baix diagrams in Ref. [5], p. 37, or in Ref. [11] the latter is cited in Ref. [8]). Table 2 shows the various compounds. 

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