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

Abstract

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.

Degree

MS

College and Department

Physical and Mathematical Sciences; Chemistry and Biochemistry

Rights

http://lib.byu.edu/about/copyright/

Date Submitted

1965-08-01

Document Type

Thesis

Handle

http://hdl.lib.byu.edu/1877/Letd702

Keywords

Spectrophotometer

Language

English

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