Characteristic of the Ag(II)/Ag(I) system in the presence of picolinic acid in water

摘要

Using IR spectrophotometry, potentiometry, and quantitative analysis, it was ascertained that the process of complexing Ag(I) ions with picolinic acid (Hpic) results in the formation of complexes such as AgH(pic)2(pH<4) and Ag(pic)2−(pH≌7). Complex Ag(II) occurs in the form Ag(pic)2oindependently of the medium. The values of conditional complex stability constants (μ=0.1) for Ag(pic)oand Ag(pic)2−found by potentiometry are as follows: β01=3.4×103and β02=1.2×106. Redox systems formed in solutions were described and their formal potentials were determined by chronovoltamperometry:$$begin{gathered} Ag(pic)_{2 }^o + e rightleftarrows Ag (pic)_2^ - {rm E}_f^o = 1.388 V vs. NHE hfill Ag(pic)_{2 }^o + e rightleftarrows Ag (pic)^o + pic^ - {rm E}_f^o = 1.240 V vs. NHE. hfill end{g