Effect of ionic strength on the polarographic half-wave potential

✍ Scribed by Richard A. Durst; David N. Hume

• Publisher: Elsevier Science
• Year: 1991
• Tongue: English
• Weight: 879 KB
• Volume: 251
• Category: Article
• ISSN: 0003-2670
• DOI: 10.1016/0003-2670(91)87109-k

✦ Synopsis

The shift in the polarographic half-wave potential caused by changes in the concentration of a non-complexing supporting electrolyte was investigated.

The depolarizer systems studied were the cadmium(H) and zinc(H) amine complex ions, and the cadmium(II), zinc(II), indium(II1) and thallium(I) aquo ions. These systems exhibited half-wave potential shifts that were dependent on five factors affected by the ionic strength of the solution: the activity and diffusion coefficients of the depolarizer ions, the activity of the complexing agent and/or water and the liquid junction potential. An equation was derived relating these factors to the half-wave potential shift and evaluated for the change in the activity coefficient of the depolarizer over the ionic strength range 4-10. As expected, the observed potential shift showed a strong correlation with the charge and primary hydration numbers of the aquo ions.