Strong electrolytes, controversy

Arrhenius himself was recalcitrant on one point he throughout insisted that his interpretation of conductivity in terms of a dissociation equilibrium applies to strong electrolytes as well as to weak ones for an account of this controversy see ref. 13. Suggestions that strong electrolytes are completely dissociated and that ionic interactions must be invoked to explain the conductivities of their solutions were made by G.N. Lewis (14-16), Niels Bjerrum (17, 18), W. Sutherland (14) and S.R. Milner (20-24). Bjerrum provided spectroscopic evidence for this point of view, and Sutherland and Milner did important work on the theory of ionic interactions. Finally, in 1923, Debye and Hllckel (25, 26) developed their comprehensive treatment of strong electrolytes. Arrhenius, however, rejected these ideas and for the most part refused to discuss them. At a meeting of the Faraday Society held in January, 1919, Arrhenius commented that Bjerrum s idea "seems not to agree very well with experiment" (27), and he maintained this position until his death in 1927. 

In this particular case, the stability of the Cu(I) intermediate depends strongly on the nature of the electrolyte. In the presence of chloride the reaction gives rise to two distinct waves in a current/potential curve, whereas in the absence of complexing ions a single two-electron process appears to occur. Studies with the ring-disc electrode [29] have established, however, that Cu(I) is formed as an intermediate with a measurable lifetime. The existence of lower valent intermediates in other metal ion electrode processes is more controversial, but it seems improbable, for example, that the reduction of Zv involves simultaneous transfer of two electrons. 

---