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A spectrophotometric study of iron-cyanide systems.|nI.|pDetermination of the formation constant of Fe [Fe(CN)₆]⁻.|nII.|pReplacement of acetylacetonate ions from Bis (Acetylacetonato) iron (II) by cyanide ion

Equilibrium constant (K) values for the formation of Turnbull's blue and Prussian blue have been determined spectrophotometrically at 25 ± 1°. A procedure was used which involved optical measurements in the presence of a large excess of one of the reagents so that the formation of the complex may be considered to be complete. The values of log K = 5.62 ± .03 and log K = 13.89 ± .03 for the formation of Turnbull's blue and Prussian blue, respectively, have been calculated. The ΔH° values for the reactions, Fe^3+ + Fe(CN)_6^4- = Fe^2+ + Fe(CN)_6^3- and Fe^2+ + Fe(CN)_6^3- = Fe[Fe(CN)_6^-], are used in appropriate combination with K values from the present study to calculate the thermodynamic values (ΔS° = 65.4 e.u., ΔH° = 0.55 kcal/mole, ΔG° = -18.95 kcal/mole, log K = 13.89) for Prussian blue formation (Fe^+3 + Fe(CN)_6^4- = Fe[Fe(CN)_6^-]), and to calculate the thermodynamic values ( ΔS° = -24.8 e.u., ΔG° = -7.68 kcal/mole, log K = 5.62) for Turnbull's blue formation. The replacement of the acetylacetonate ions of the bis(acetyl-acetonato)iron(II) species by cyanide ions has been studied by spectro-photometric titration, stoichiometric titration, and elemental analysis.

Identiferoai:union.ndltd.org:BGMYU2/oai:scholarsarchive.byu.edu:etd-9502
Date01 August 1965
CreatorsWu, Yulin
PublisherBYU ScholarsArchive
Source SetsBrigham Young University
Detected LanguageEnglish
Typetext
SourceTheses and Dissertations
Rightshttp://lib.byu.edu/about/copyright/

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