Acid–base behaviour of the ferrocyanide ion in perchloric acid media potentiometric and spectrophotometric study

作者：Pedro L. Domingo, Begoña Garcı́a, José Maria Leal · 发表于：Canadian Journal of Chemistry · 年份：1987 · DOI：10.1139/v87-102 · 被引用次数：28 · 研究领域：Analytical Chemistry and Sensors、Electrochemical Analysis and Applications、Inorganic and Organometallic Chemistry

Ferrocyanide ion behaves as a tetravalent Brønsted base and can react with four protons, forming ferrocyanic acid. By potentiometric and spectrophotometric techniques it is shown that the first two protonation equilibria overlap, as do the third and fourth equilibria. The two techniques yield identical results when processed with the inclusion of non-ideality terms. The method of "separation of equilibria" is proposed to allow separate study of each of the overlapping equilibria. Values of pK1 = −2.54 ± 0.10, pK2 = −1.08 ± 0.03, pK3 = 2.65 ± 0.02, and pK4 = 4.19 ± 0.02 were obtained.