THE CHEMISTRY OF IRIDIUM IN BASIC AQUEOUS SOLUTION: A POLAROGRAPHIC STUDY

1966 ◽  
Vol 44 (4) ◽  
pp. 515-520 ◽  
Author(s):  
Gary Van Loon ◽  
John A. Page
Keyword(s):  
Aqueous Solution ◽  
Reference Electrode ◽  
Hydrogen Ion ◽  
Saturated Calomel Reference Electrode ◽  
Reduction Wave ◽  
Polarographic Study ◽  
Polarographic Behavior ◽  
Diffusion Controlled ◽  
Oxidation Wave ◽  
Basic Solutions

The polarographic behavior of iridium(IV) has been studied in basic solutions at 25 °C at an ionic strength maintained with sodium chloride at 0.50 M. Between pH 11.3 and 13.0, a reversible, diffusion-controlled, one Faraday per mole reduction wave was obtained. The E1/2 was −0.60 V versus a saturated calomel reference electrode at pH 12.0; a shift of −57 mV per pH unit indicated that one hydrogen ion is involved in the reduction. With basic solutions of iridium(III), the corresponding oxidation wave was obtained, but the metal was easily air oxidized. The basic iridium(IV) species gave an absorption peak at 313 mμ. The rate of formation of the basic iridium(III) complex from an acid iridium(III) solution was found to be more rapid than that of the basic iridium(IV) complex from an acid iridium(IV) solution. The reaction of iridium (IV) with ethylenediaminetetracetate was also studied.

Polarographic Study of the Complexation of Na+ and K+ Ions by Dibenzo-18-crown-6 in Non-Aqueous Solution

1990 ◽  
Vol 43 (12) ◽  
pp. 2003 ◽  
Author(s):  
E Lada ◽  
A Urbanczyk ◽  
MK Kalinowski
Keyword(s):  
Aqueous Solution ◽  
Stability Constants ◽  
Polarographic Study

Complexes of Na+ and K+ ions with dibenzo-18-crown-6 (6,7,9,10,17,18,20,21-octahydro-dibenzo[ b,k ] [1,4,7,10,13,16] hexaoxacyclooctadecin ) were studied by polarography in several non-proton-donating media. Their stability constants are strongly influenced by the solvents, and vary inversely with the Gutmann donicity scale and with the Persson HDS parameter which is a measure of the hardness for these solvents.

scholarly journals A Polarographic Study of Amino Acids in Aqueous Solution

1971 ◽  
Vol 44 (7) ◽  
pp. 1984-1986 ◽  
Author(s):  
Shizuo Fujiwara ◽  
Yoshio Umezawa ◽  
Hidehiro Ishizuka
Keyword(s):  
Aqueous Solution ◽  
Amino Acids ◽  
Polarographic Study

SOME THEORETICAL ASPECTS OF ELECTRON-TRANSFER PROCESSES IN AQUEOUS SOLUTION

1959 ◽  
Vol 37 (1) ◽  
pp. 138-147 ◽  
Author(s):  
Keith J. Laidler
Keyword(s):  
Aqueous Solution ◽  
Electron Transfer ◽  
Free Energy ◽  
Energy Of Activation ◽  
Theoretical Treatment ◽  
Free Energy Of Activation ◽  
Diffusion Controlled ◽  
Entropy Of Activation ◽  
Pass Through ◽  
Electron Transfer Processes

A theoretical treatment has been developed for the rates of electron-transfer reactions in aqueous solution, with particular reference to the ferric–ferrous system. The reactions are considered to be diffusion-controlled processes, the approach of the ions being hindered by the electrostatic repulsion between them. Calculations have been made of the free energy of the diffusion process and for the repulsion, account being taken of the variation in dielectric constant with the electric field. The form of the potential-energy barrier between the ions is calculated for various separations, and the transmission coefficient calculated using the quantum-mechanical expression corresponding to a rectangular barrier. The total free energy of activation for the reaction, which is the sum of the contributions due to diffusion, repulsion, and tunnelling, is found to pass through a minimum at a separation of about 4 Å. The calculated free energy of activation for the reaction is 15.4 kcal, in good agreement with the experimental value of 16.8 kcal. The energy and entropy of activation for the reaction are also briefly discussed.

Kinetics and Mechanism of the Thermal Decomposition of Hexaamminecobalt(III) and Aquopentaamminecobalt(III) Ions in Acidic Aqueous Solution

1974 ◽  
Vol 52 (15) ◽  
pp. 2751-2759 ◽  
Author(s):  
Anthony Martin Newton ◽  
Thomas Wilson Swaddle
Keyword(s):  
Aqueous Solution ◽  
Thermal Decomposition ◽  
Rate Coefficient ◽  
Initial Step ◽  
Hydrogen Ion ◽  
Minor Amount ◽  
Acidic Aqueous Solution ◽  
First Order ◽  
Independent Path ◽  
A Minor

The initial step in the thermal decomposition of Co(NH3)63+ in acidic aqueous solution is the replacement of NH3 by H2O, which occurs by a hydrogen-ion independent path, first order in complex, with rate coefficient k1 = 7.9 × 10−5 s−1 (140.4°), ΔH* = 36.6 kcal mol−1 and ΔS* = 10.7 cal deg−1 mol−1 in 0.1 M HClO4. For Co(NH3)5OH23+, there is a similar initial aquation path with k1 = 12.6 × 10−5 s−1 (140.6°), ΔH* = 41.9 kcal mol−1 and ΔS* = 24 cal deg−1 mol−1 and also a path first order in complex but inverse first order in [H+] with k2′ = 6.2 × 10−1 M s−1 (140.6°), ΔH* = 43.5 kcal mol−1 and ΔS* = 26.7 cal deg−1 mol−1 in perchlorate media of ionic strength 1.0 M. The effects of electrolyte type and concentration on the rates of these reactions have been examined. Subsequent aquation steps are relatively rapid because of the predominance of inversely [H+]-dependent pathways and are followed by redox to Co(H2O)62+, NH4+, N2, N2O, and a minor amount of O2. A mechanism involving OH and NH2 radicals is proposed for the redox step.

Polarographic Study of the Electrode Reaction of Zn(II) in Formamide and Dimethylformamide

1975 ◽  
Vol 30 (5-6) ◽  
pp. 350-354 ◽  
Author(s):  
Sudhindra Swarup Sharma ◽  
Mukhtar Singh
Keyword(s):  
Kinetic Parameters ◽  
Organic Solvents ◽  
Metal Ion ◽  
Supporting Electrolyte ◽  
Electrode Reaction ◽  
Polarographic Study ◽  
Aqueous Mixtures ◽  
Diffusion Controlled ◽  
And Diffusion

The reduction of Zn(II) at the d.m.e. has been studied in aqueous mixtures of formamide and dimethylformamide. The general polarographic characteristics have been determined, using 0.1 M NaNO3 as the supporting electrolyte. The reduction of Zn(II) in these organic solvents is irreversible and diffusion controlled. The kinetic parameters, αna and kf,h have been calculated separately by KOTECKY and DELAHAY treatments. The change of polarographic characteristics and kinetic parameters is explained in terms of solvation of the metal ion in these solvents. The electrocapillary curves in the presence of these solvents have also been studied.

Modeling the Diffusion Mechanism and the Reaction Kinetics for the Photocatalytic Degradation of Acid Red 151 Aqueous Solutions by ZnO: Comparison of Linear and Non-Linear Methods

2007 ◽  
Vol 10 (2) ◽  
Author(s):  
K. Vasanth Kumar ◽  
K. Porkodi
Keyword(s):  
Aqueous Solution ◽  
Diffusion Coefficient ◽  
Aqueous Solutions ◽  
Photocatalytic Degradation ◽  
Reaction Kinetics ◽  
Diffusion Mechanism ◽  
Batch Processes ◽  
Average Diffusion Coefficient ◽  
Diffusion Controlled ◽  
Average Diffusion

AbstractBatch processes were carried out for the photocatalytic degradation of Acid Red 151 from its aqueous solution using ZnO catalyst at different initial dye concentrations. The process was found to be diffusion controlled for the first 15-20 minutes (before irradiation) with an average diffusion coefficient of 6.759 × 10

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