Reduction of indium(III) at dropping mercury electrode in the presence of pyridine in aqueous and ethanol–water media

2010 ◽  
Vol 75 (6) ◽  
pp. 653-663 ◽  
Author(s):  
Vinita Sharma ◽  
Krishna D. Gupta
Keyword(s):  
Mercury Electrode ◽  
Complexation Reaction ◽  
Complex Species ◽  
Diffusion Controlled ◽  
Straight Line ◽  
Half Wave ◽  
Dropping Mercury Electrode ◽  
Water Media ◽  
Single Complex ◽  
The Stability

The reduction of indium(III) at dropping mercury electrode in aqueous as well as in 25% ethanol–water media in the presence of pyridine has been studied at a constant ionic strength (0.1 M KNO3) and at 30 and 40 °C. The reduction is diffusion-controlled but the electrode process is quasi-reversible in both media. The reversible half-wave potential values,E1/2r, have been obtained by Gelling’s method. The plot ofE1/2r versus pyridine concentration is a straight line and the number of ligands,j, was determined from the slope. This shows the formation of a single complex. The stability constant has been determined by Lingane’s method. In(III) forms one complex species with composition 1:1, [In(py)]3+. The values of thermodynamic parameters ΔG, ΔHand ΔSof the complexation reaction have also been determined at 30 °C.

Cathodic action of lead malate complexes at the dropping mercury electrode

1973 ◽  
Vol 26 (5) ◽  
pp. 971 ◽  
Author(s):  
SC Khurana ◽  
CM Gupta
Keyword(s):  
Stability Constants ◽  
Mercury Electrode ◽  
Reduction Reaction ◽  
Ligand Concentration ◽  
Wave Potential ◽  
Half Wave Potential ◽  
Half Wave ◽  
Dropping Mercury Electrode ◽  
The Stability

The electrode reduction reaction of lead malate, involving deprotonated malate ion and a proton, between pK1 and pK2 values of the acid has been investigated. At pH < pK1 protonated ion participates and a proton is involved. The effect of ligand concentration on the half-wave potential of Pb2+ has been investigated and the stability constants of species so formed computed.

The determination of the stoichiometry and stability constant of weak complexes in solution: a restatement of the "straight-line" method

1983 ◽  
Vol 61 (6) ◽  
pp. 1100-1102 ◽  
Author(s):  
Aurelio Beltrán-Porter ◽  
José A. Ramírez
Keyword(s):  
Stability Constant ◽  
Stoichiometric Ratio ◽  
Complex Species ◽  
Line Method ◽  
Straight Line ◽  
Weak Complexes ◽  
The Stability ◽  
Degree Of Condensation ◽  
Straight Line Method

Usually, to establish the degree of condensation of a complex species in solution, primarily when it is a weak complex, is more cumbersome than to determine the stoichiometric ratio itself. The present work describes a modification of the Asmus method in order to render it suitable for the determination of the actual stoichiometric coefficients and the stability constant of weak complexes whatever the degree of condensation may be.

Polarography of n-butylthioglycolate in aqueous media, methanol, and acetonitrile

1984 ◽  
Vol 62 (9) ◽  
pp. 1817-1821
Author(s):  
K. C. Gupta ◽  
Kalpana K. Sharma
Keyword(s):  
Aqueous Media ◽  
Mercury Electrode ◽  
Wave Characteristics ◽  
Anodic Wave ◽  
Diffusion Controlled ◽  
Dropping Mercury Electrode ◽  
Drop Time ◽  
And Diffusion ◽  
Mechanism Of The Reaction

The polarographic behaviour of n-butylthioglycolate (RSH) at the DME in aqueous media, methanol, and acetonitrile has been investigated in the presence of 0.1 M KNO3 and 0.01% thymol. The effect of pH, concentration of RSH, and drop time on the wave characteristics and the mechanism of the reaction occurring at the surface of the mercury drop have been studied. Well-defined reversible and diffusion-controlled anodic waves were obtained in aqueous media (pH 4.2), 40% methanol (pH 3.22), and 40% acetonitrile (pH 2.96). Mathematical and analytical evidence was obtained to show that the anodic wave of RSH at a dropping mercury electrode in aqueous media, 40% methanol, and 40% acetonitrile is due to the formation of the mercury complex RSHg. The dissociation constant (pK) of the mercapto group in n-butylthioglycolate is 9.6 and the diffusion coefficient in the different media are 1.17 × 10−6 cm2 s−1 (in aqueous media) 1.23 × 10−6 cm2 s−1 (in 40% methanol), and 2.43 × 10−6 cm2 s−1 (in 40% acetonitrile). The linearity of id with RSH concentration provides a rapid and precise method for the determination of RSH, down to 0.4 mM in aqueous media, methanol, and acetonitrile.

scholarly journals Reduction of Cd(II) Ions in the Presence of Tetraethylammonium Cations. Adsorption Effect on the Electrode Process

Electrochem ◽  
2021 ◽  
Vol 2 (3) ◽  
pp. 415-426
Author(s):  
Juan Torrent-Burgués
Keyword(s):  
Mercury Electrode ◽  
Reduction Process ◽  
Inhibitory Effect ◽  
Electrode Process ◽  
Adsorption Effect ◽  
A Value ◽  
Half Wave ◽  
Dropping Mercury Electrode ◽  
Electrode Coverage ◽  
Isotherm Equations

The effect of the adsorption of tetraethylammonium (TEA) cations, which present both ionic and organic characteristics, on the reduction of Cd(II) ions have been studied from dc and ac measurements at the dropping mercury electrode. The resistance to the charge transfer (Rct) and Warburg coefficient (σ) parameters have been determined through impedance measurements. Thus, the global velocity constant has been obtained. The reduction process of Cd(II) in perchloric media is reversible and is affected by the adsorption of TEA cations, especially at high TEA concentrations. Values of E1/2, half wave potential, and DO, diffusion coefficient, obtained from both dc and ac measurements agree. The velocity constants show a decrease as TEA concentration increases, with values ranging from 0.6 to 0.01 cm·s−1. The inhibitory effect of TEA adsorption on the electrode process and the relationship between electrode coverage, θ, and velocity constants, K, using several isotherm equations, have been discussed. The best fit was obtained with the equation K = 0K(1 − θ)a with an a value close to three, indicating a blocking effect and electrostatic repulsion due to TEA.

Electrochemical Investigations of the Nickel(II)-Penicillamine System. 2. Direct Identification of Complex Species Involved in Catalytic Nickel Reduction on the Dropping Mercury Electrode

1998 ◽  
Vol 63 (7) ◽  
pp. 995-1006 ◽  
Author(s):  
Florinel G. Banica ◽  
Ana Ion
Keyword(s):  
Mercury Electrode ◽  
Formation Constants ◽  
Active Species ◽  
Electrode Process ◽  
Ligand Complex ◽  
Direct Identification ◽  
Complex Species ◽  
Nickel Ions ◽  
Dropping Mercury Electrode ◽  
System 2

The catalytic polarographic nickel prewave was investigated by making appropriate correlations between prewave current and complex species concentrations as calculated by means of available formation constants. It was concluded that the active species is (D-penicillaminato-N,S)nickel(II) [NiL], whereas the bis-ligand complex, [NiL2]2-, is inert and does not play any role in the electrode process. The catalytic character of the electrode process originates from the regeneration of [NiL] by the reaction of adsorbed ligand molecules with free nickel ions available in the bulk of the solution. Conversely, all the complex species in the Ni2+-cysteine system are labile. Consequently, the reaction mechanism in this case may include the dissociation of the complex [NiL2]2- as an alternative path for the generation of the active species, [NiL]. The bell-shaped form of the prewave was interpreted in terms of potential-dependent catalyst adsorption.

Polarographic and Voltammetric Determination of Chlorobenzene, Benzyl Chloride and Melphalan

1992 ◽  
Vol 57 (3) ◽  
pp. 450-456 ◽  
Author(s):  
Jiří Barek ◽  
Jaroslav Matějka ◽  
Jiří Zima
Keyword(s):  
Benzyl Chloride ◽  
Mercury Electrode ◽  
Differential Pulse ◽  
Differential Pulse Polarography ◽  
Water Medium ◽  
Pulse Polarography ◽  
Half Wave ◽  
Dropping Mercury Electrode ◽  
Pulse Voltammetry

Conditions were found for the determination of chlorobenzene and benzyl chloride in dimethylformamide and of Melphalan in ethanol-water medium (4 : 1) using tast polarography at a classical dropping mercury electrode in the concentration range 1 . 10-3 - 2 . 10-5 mol l-1. Differential pulse polarography permits the range for the determination of benzyl chloride to be extended to 1 . 10-5 - 2 . 10-6 mol l-1. The use of fast scan differential pulse voltammetry and linear scan voltammetry at a hanging mercury drop electrode did not lead to an increase in the sensitivity of the determination because of the very negative half-wave potential values and high irreversibility of the processes involved.

Mechanism of 2-quinizarinsulphonic acid reduction on a mercury electrode

1981 ◽  
Vol 59 (8) ◽  
pp. 1201-1204 ◽  
Author(s):  
F. Capitan ◽  
A. Guiraum ◽  
J. L. Vilchez
Keyword(s):  
Mercury Electrode ◽  
Sulphonic Acid ◽  
Kinetically Controlled ◽  
Diffusion Controlled ◽  
Dropping Mercury Electrode ◽  
Reaction Orders ◽  
Second Wave ◽  
Acid Reduction

The reduction of the 1,4-dihydroxyanthraquinone-2-sulphonic acid (quinizarinsulphonic acid) at a dropping mercury electrode has been investigated. The reduction takes place in two monoelectronic steps and show E1/2 values vs. sce (E1/2)1 = −0.380 V and (E1/2)2 = −1.045 V at pH 4.60. The first wave is diffusion controlled, while the second wave is kinetically controlled. The reagent captures one electron and one proton to form the semiquinonic system. The semiquinone is dimerized. The dimer captures one electron and one proton, per molecule, to form the hydroquinone. The reaction orders, together with Tafel's slopes, have been calculated.

POLAROGRAPHIC DETERMINATION OF BENZOYL PEROXIDE AND CUMENE HYDROPEROXIDE

1951 ◽  
Vol 29 (1) ◽  
pp. 54-59 ◽  
Author(s):  
Paul A. Giguère ◽  
D. Lamontagne
Keyword(s):  
Dissolved Oxygen ◽  
Benzoyl Peroxide ◽  
Mercury Electrode ◽  
Cumene Hydroperoxide ◽  
Polarographic Determination ◽  
Polarographic Method ◽  
Organic Peroxides ◽  
Half Wave ◽  
Dropping Mercury Electrode

Benzoyl peroxide and cumene hydroperoxide (CHP) are reduced at the anodically polarized dropping mercury electrode, the former at about +0.3 volt vs. S.C.E., and the latter at +0.1 v. Their half-wave potentials as well as that of the two reduction steps of dissolved oxygen are gradually shifted towards more negative values with increasing concentration of organic peroxides. The polarographic method is suitable for determining these peroxides in concentrations up to 2 × 10−3 mole per liter. Dissolved oxygen does not interfere seriously with the analyses.

Direct current polarography of the ferrous-ferric oxolate system in the presence of alternating voltages

1958 ◽  
Vol 11 (1) ◽  
pp. 9
Author(s):  
P Beckmann ◽  
GS Buchanan
Keyword(s):  
Direct Current ◽  
Active Substance ◽  
Mercury Electrode ◽  
Surface Active Substance ◽  
Active Materials ◽  
Wave Potential ◽  
Half Wave ◽  
Dropping Mercury Electrode ◽  
Surface Active ◽  
Alternating Voltage

The effect of the superposition of a small alternating voltage on the normal direct voltage applied to the dropping mercury electrode (D.M.E.) was investigated in the case of the ferrous-ferric oxalate system. The wave obtained was of the type found previously for ions which are reversibly reduced at the D.M.E. (e.g. Cd++ etc.). That is, the rectification of the A.C. produced a D.C. wave (the Z wave) which crossed the normal D.C. wave (the Y wave) at the half-wave potential (E�), When surface active materials were added (e.g. cyclohexanol) the reduction became " irreversible " and at certain concentrations of the surface active substance a maximum appeared on the Y wave of a somewhat unusual nature. The effect of a superposed alternating voltage was studied in these cases and it was found that the adsorption of the cyclohexanol was influenced by the presence of the alternating voltage.

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