Sulfite-thiosulfate electrolyte

A comparison of anodic polarization curves for various reducing agents shows that the reducing power in a base electrolyte containing sulfite, thiosulfate, and ammonium chloride at pH 6.0 and at 60 °C decreases in the order ascorbate > thiourea > hydrazine. These polarization curves are reproduced in Fig. 41, which demonstrates that hydroxylamine and formaldehyde are not useful as reducing agents in this system. 

Hydroxyethyl cellulose has good tolerance for dissolved electrolytes, although it may be salted out of solution when mixed with certain salt solutions. For example, the following salt solutions will precipitate a 10% w/v solution of Cellosize WP-09 and a 2% w/v solution of Cellosize WP-4400 sodium carbonate 50% and saturated solutions of aluminum sulfate ammonium sulfate chromic sulfate disodium phosphate magnesium sulfate potassium ferrocyanide sodium sulfate sodium sulfite sodium thiosulfate and zinc sulfate. 

The gold thiosulfate complex Au(S203)2 has a fairly high stability constant (see Table 112), and a wide pH range of thermodynamic stability. Despite these characteristics, a gold thiosulfate electrolyte has never been successfully developed because of the limited stability of the ligand. In lact, at neutral or add pH, thiosuUate is unstable towards decomposition in colloidal sulfur and sulfite [27] ... 

Indirect evidence for the proposed mechanism was found in the adsorption behavior of the thiosulfate anion and the Au(S203)2 complex at gold surfaces [57,58]. Similar conclusions about the nature of the gold complex and its role as electroactive species in the mixed electrolyte were reached in a voltammetric study of the thiosulfate-sulfite bath at a rotating disk electrode [59]. 

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