Stepwise formation constants of complex ions: A student experiment

1967 ◽  
Vol 44 (1) ◽  
pp. 46 ◽  
Author(s):  
William B. Guenther
Keyword(s):  
Formation Constants ◽  
Complex Ions ◽  
Stepwise Formation

Solubility and Complex-Ion Equilibria

2021 ◽  
pp. 313-324
Author(s):  
Christopher O. Oriakhi
Keyword(s):  
Metal Complexes ◽  
Solubility Product ◽  
Formation Constants ◽  
Aqueous Systems ◽  
Complex Ions ◽  
Ionic Compounds ◽  
Molar Solubility ◽  
Solubility Product Constant ◽  
Complex Ion

Solubility and Complex-Ion Equilibria broadens the previous chapter’s coverage of equilibria to include aqueous systems containing two or more solutes of slightly soluble ionic compounds and the formation of metal complexes in solution. Solubility equilibria which allow quantitative predictions of how much of a compound will dissolve under given conditions are covered. The meaning of the solubility product constant (K sp) and how to calculate it from molar solubility values is presented. Also discussed is determination of molar solubility from K sp. Calculations demonstrate how to predict the formation of a precipitate by comparing the ion product or solubility quotient (Q) with K sp. Formation constants of complex ions and calculations involving complex ion equilibria are explained.

Stabilities of Vanadyl Complexes with Methionine, Phenylalanine, and Threonine

1974 ◽  
Vol 29 (7-8) ◽  
pp. 336-338
Author(s):  
B.S. Sekhon ◽  
S.L. Chopra
Keyword(s):  
Free Energy ◽  
Ionic Strength ◽  
Stability Constants ◽  
Thermodynamic Stability ◽  
Chloride Solution ◽  
Formation Constants ◽  
Potassium Chloride Solution ◽  
Vanadyl Complexes ◽  
Overall Stability ◽  
Stepwise Formation

Abstract Stepwise formation constants corresponding to 1:1 vanadyl complexes with methionine, phenylalanine and threonine have been determined at 25 °C, and at various ionic concentrations, viz. 0.01, 0.1 and 0.3 ᴍ , maintained by the addition of potassium chloride solution. Thermodynamic stability constants have been obtained by extrapolation of log K values to zero ionic strength. Logarithms of the overall stability constants (log K (u = 0)) are 7.72 for methionine, 7.70 for phenyl­alanine and 7.44 for threonine complexes. The corresponding free energy changes (⊿G0) are - 10.53, - 10.51, - 10.15 kcal-mol-1 respectively.

Thermodynamic Study of Ce4+ /Ce3+ Redox Reaction in Aqueous Solutions at Elevated Temperatures: 1. Reduction Potential and Hydrolysis Equilibria of Ce4+ in HCIO4 Solutions

1992 ◽  
Vol 47 (9) ◽  
pp. 974-984 ◽  
Author(s):  
B. A. Bilal ◽  
E. Müller
Keyword(s):  
Redox Reaction ◽  
Elevated Temperatures ◽  
Formation Constants ◽  
Cyclic Voltammetric ◽  
Voltammetric Measurement ◽  
Constant Potential ◽  
Increasing Temperature ◽  
Aqueous Hclo ◽  
Stepwise Formation ◽  
Cyclic Voltammetric Measurement

AbstractThe redox potential (E) of the couple Ce4+/Ce3+ has been determined up to 368 K by means of cyclic voltammetric measurement in aqueous HClO4 solutions with cHClO4 decreasing from 7.45 to 0.023 mol kg-1 . A constant potential of (1.741 V)298 K, resp. (1.836 V)368K, indicating the existence of pure unhydrolysed Ce4+ was obtained at cHClO4 ≥ 6.05 m. At lower HClO4 concentration, the potential as a function of the HClO4 molality, as well as of the pH shows 4 further distinct steps. At 298 K, for instance, the potential became nearly constant at pH values of 0.103, 0.735,1.115, after which it drastically decreased, respectively at 1.679, just before the precipitation of Ce(OH)4 occurred. The curves indicate obviously the stepwise formation of the Ce(IV) mono-, di-, tri- and tetrahydroxo complexes. The slope of the curves E vs. pH increased gradually with increasing temperature. ΔS and ΔH of the redox reaction were determined as functions of T at the different HClO4 concentrations. ΔSis positive at cHClO4 > 1.85 m and turns to be negative at lower concentrations. ΔHis negative at all HClO4 concentrations studied. The cumulative formation constants ßi, of the Ce(IV) hydroxo complexes and the corresponding hydrolysis constants (Kh)i were calculated. An unusual decrease of ßi with increasing temperature has been discussed

Study of iron(II) complexes with halides and thiocyanate in acetonitrile

1970 ◽  
Vol 48 (9) ◽  
pp. 1414-1419 ◽  
Author(s):  
Byron Kratochvil ◽  
Robert Long
Keyword(s):  
Formation Constants ◽  
Ratio Method ◽  
Mole Ratio Method ◽  
Stepwise Formation

In acetonitrile, iron(II) forms stable 1:1 complexes with chloride, bromide, and iodide and both 1:1 and 1:2 complexes with thiocyanate. Stepwise formation constants for the complexes were determined spectrophotometrically by a mole-ratio method. The log K values are: FeCl+, 5.8; FeBr+, 5.5; FeI+,4.3; Fe(SCN)+, 5.5; and Fe(SCN)2, 3.7.

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