Formation equilibria of vanadium(V) species in different ionic media: Salt effect and protonation constant

The influence on ionic strength of protonation of vanadate ion is reported in sodium perchlorate and sodium chloride solutions as background electrolytes. The measurements have been performed at 25 °C and various ionic strengths using a combination of potentiometric and spectrophotometric techniques. The overall analysis of the present and the previous data dealing with determination of formation constants at different ionic strengths allowed us to obtain a general equation, by which a formation constant determined at a fixed ionic strength can be recalculated, with a good approximation for another ionic strength, if the ionic strength for sodium perchlorate or sodium chloride is in the 0.1-1.0 mol dm− 3 range.