The polarography of glycine metal complexes and the determination of stepwise formation constants

1961 ◽  
Vol 14 (4) ◽  
pp. 562 ◽  
Author(s):  
DP Mellor ◽  
HA McKenzie
Keyword(s):  
Metal Complexes ◽  
Formation Constants ◽  
Substantial Agreement ◽  
Titration Method ◽  
Ph Titration ◽  
Polarographic Behaviour ◽  
The Stability ◽  
Titration Technique ◽  
Stepwise Formation

The polarography of metal-glycine complexes has been studied with a view to assessing its usefulness in measuring the stability of metal complexes, especially the stepwise formation constants. It is shown that the equation derived by De Ford and Hume (1951) may be transformed in a way that makes possible the calculation of both overall and stepwise stoichiometric constants from experimental data obtained with solutions of constant ionic strength. Problems in the use of maximum suppressors and buffer ions are considered. Stoichiometric stepwise stability constants for the glycine complexes of copper(II) and cadmium(II) have been determined : (i) polarographically and (ii) by the pH- titration method of Irving and Rossotti (1954a, 1954b). The values obtained by the two methods agree reasonably well. Problems of hydrolysis and precipitation arise with t8he lead(II) complexes. The zinc(II) complexes exhibit anomalous polarographic behaviour. The reasons for this behaviour are briefly discussed. Although the polarographic technique is capable of yielding values for step constants in substantial agreement with those obtained by the pH-titration technique, there is evidence that it in not so generally applicable as the latter.

Physico-chemical investigation on the complexes of indium(III) with Mercapto-, Hydroxy-, and Amino-substituted propionic acid

1972 ◽  
Vol 25 (5) ◽  
pp. 929 ◽  
Author(s):  
R Sarin ◽  
KN Munshi
Keyword(s):  
Formation Constants ◽  
Alternative Methods ◽  
Potentiometric Studies ◽  
Ph Titration ◽  
Physico Chemical ◽  
Different Temperatures ◽  
Indium 111 ◽  
The Stability ◽  
Titration Technique ◽  
Stepwise Formation

Potentiometric studies have been carried out on the metal complexes of indium(111) with β-mercaptopropionic, β-hydroxypropionic, and β-aminopropionic acid. The Calvin-Bjerrum pH-titration technique, as used by Irving and Rossotti, has been applied to determine the stepwise formation constants of the complexes. The logK values have been computed by alternative methods. Thermodynamic formation constants have been obtained by extrapolation of the values at various ionic concentrations. The values of overall changes in ΔG, ΔH, and ΔS accompanying complex formation have been evaluated at three different temperatures at an ionic strength of 0.lM (NaClO4). The stability constant of the indium(111) complex decreases as the subsituted group changes from SH to OH to NH2.

scholarly journals Potentiometric studies on complexes of Cr (Ⅲ) and Zr (IV)with some carboxylic acids

2015 ◽  
Vol 3 (1) ◽  
pp. 25 ◽  
Author(s):  
Abdalazeem Omar ◽  
Elmugdad Ali
Keyword(s):  
Stability Constants ◽  
Transition Elements ◽  
Ph Titration ◽  
Oxalacetic Acid ◽  
The Stability ◽  
Titration Technique ◽  
Metal Ligand ◽  
Sensitive Method ◽  
Good Agreement

<p>The present work, deals with the study of proton-ligand (pK) and metal-ligand (logK) of acetic acid, oxalic acid, and oxalacetic acid with Cr (Ⅲ) and Zr (IV) by potentiometric titration technique. The stoichiometries and stability constants of these complexes were evaluated, usingCalvin-Bjerrum pH-titration technique as adopted by Irriving and Rossotti.</p><p>Graphic and algebraic methods have been employed, for determination of the stability constants, in purpose to select the most accurate and sensitive method. Furthermore, aiming to determine, the factor that effectingthe precision of those methods under investigation, and to compare the complexes of these ligands with first and second series transition elements of D-block Cr and Zr taken as an example. The obtained results were in a good agreement with each other.</p>

scholarly journals Stability Constants of Some Biologically Important Pyrazoles and Their Ni2+Complexes in Different Dielectric Constant of Medium

2012 ◽  
Vol 9 (2) ◽  
pp. 637-641 ◽  
Author(s):  
S. D. Deosarkar ◽  
A. L. Puyad ◽  
S. A. Chavan
Keyword(s):  
Dielectric Constant ◽  
Ionic Strength ◽  
Stability Constants ◽  
Metal Ion ◽  
Formation Constants ◽  
Water Mixture ◽  
Electrostatic Forces ◽  
Ph Titration ◽  
Titration Technique

The proton-ligand stability constants of some biologically important new pyrazoles and formation constants of their complexes with Ni(II) were determined at 0.1 mol dm-3ionic strength and at 303.15 K in different dielectric constant of dioxane-water mixture by potentiometric method. The Calvin-Bjerrum's pH-titration technique as used by Irving and Rossotti was used for determination of stability constants. The results enabled to study the electrostatic forces of attraction between metal ion and ligand with changes in dielectric constant of the medium.

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.

scholarly journals Analysis of alkyl ketene dimer (AKD) by potentiometric titration

1994 ◽  
Vol 72 (2) ◽  
pp. 274-278 ◽  
Author(s):  
S. Nyarku ◽  
B. Bruce Sitholé
Keyword(s):  
Potentiometric Titration ◽  
Glacial Acetic Acid ◽  
Hydrolysis Product ◽  
Organic Base ◽  
Alkyl Ketene Dimer ◽  
Titration Method ◽  
Potentiometric Titration Method ◽  
The Stability ◽  
Excess Base

A simple and precise potentiometric titration method has been developed for the determination of milligram quantities of alkyl ketene dimer (AKD) in non-aqueous solvents. It involves the addition of chloroform solutions of AKD to an excess of an organic base followed by the titration of excess base with perchloric acid in glacial acetic acid. The method was used to determine non-reacted AKD extracted from hand-sheets: our results agreed with those obtained by capillary gas chromatography. The method was also used to monitor the stability of AKD formulations. Wood resin components and stearone, a hydrolysis product of AKD, do not interfere.

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