Effects of electrolytes upon potential-pH relation of synthetic beta manganese dioxide

✍ Scribed by I. Tari; T. Hirai

• Publisher: Elsevier Science
• Year: 1982
• Tongue: English
• Weight: 393 KB
• Volume: 27
• Category: Article
• ISSN: 0013-4686
• DOI: 10.1016/0013-4686(82)80073-x

✦ Synopsis

AImtract

-The pi+-response of electrode potential of a synthetic beta manganese dioxide was obtained as -O.OtiOV.pH-' inconcentrated ZnCl, solutions. TbepH-response of -0.060 V pH -1 was also obtained in (C,H,),NClO, solutions in the pH range 47 where the pH-response in L M NH&l was -O.lOOV.pH-'. Such pH-response seemed to be resulted from inhibiting completely disproportionation reaction of trivalent manganese being present in the MnOs sample. Accordingly, Mn '+ ions which would cause a high responsibility of potential on pH were not formed. The effect of ZnCl, seemed to be based on ion-exchange adsorption of Zn2 + ion onto the oxide surface to inhibit the disproportionation reaction. On the other hand, the effect of (C,H&NC104 was based on both univalency and large radius of cation and anion which were not adsorptive on MnOs surface and not a proton donor for the disproportionation reaction.

The pH-response in the presence of Mn"' waaclose to the theoretical valueof -0.118 V.pH-' at 25"Cas expected. Effects of ZnClz upon such pH-response were also examined.