scholarly journals KINETIC MODEL OF THIOUREA DIOXIDE DECOMPOSITION IN AQUEOUS SOLUTIONS OF DIFFERENT ACIDITY

2018 ◽  
Vol 61 (12) ◽  
pp. 87-93
Author(s):  
Yuri V. Polenov ◽  
Gleb A. Shestakov ◽  
Elena V. Egorova
Keyword(s):  
Kinetic Model ◽  
Rate Constants ◽  
Silver Chloride ◽  
Mercury Electrode ◽  
Calculated Data ◽  
Correlation Coefficients ◽  
F Test ◽  
Thiourea Dioxide ◽  
Dropping Mercury Electrode ◽  
The Individual

A stoichiometric mechanism for full thiourea dioxide decomposition in aqueous solution under pH of 4.0 is proposed based on dependences of concentrations of thiourea dioxide and its decomposition products on the time and literature data. The concentration of thiourea dioxide was measured via iodometry, while the intermediates were quantified using the polarography. Polarography was carried out in glass two-electrode electrochemical cell by means of PU-1 polarograph in differential mode. Dropping mercury electrode was used as working one and silver chloride as a reference one. Rate constants for individual stages are obtained via mathematical modeling, presented a system of differential equations. Absolute errors of rate constants, correlation coefficients, and F-factors were also calculated. Verification of supposed kinetic model was conducted using the comparison between experimental and calculated concentrations, F-test and the calculated values of correlation coefficients of the individual stages of the process. Supposed kinetic model of decomposition consists of a number of consequent stages including various compounds such as sulfur monoxide, thiosulfuric, sulfuric, dithionic, hydrosulfuric acids as intermediates was used for previously obtained data for pH of 8.85. To test the universality of supposed model, we simulated kinetics of thiourea dioxide decomposition reaction at pH of 8.85. Experimental kinetic data were taken from literature. The initial approximations of the individual stages constants were taken from previous calculations. Analysis of calculated data: concentration values, F-test, correlation coefficients allowed to conclude about the applicability of proposed mechanism for the process of thiourea dioxide decomposition in a weakly alkaline medium.

scholarly journals KINETICS OF THIOUREA DIOXIDE DECOMPOSITION IN WATER-ETHANOL-AMMONIA SOLUTION

2019 ◽  
Vol 62 (8) ◽  
pp. 95-101
Author(s):  
Yuri V. Polenov ◽  
Elena V. Egorova ◽  
Konstantin S. Nikitin
Keyword(s):  
Rate Constants ◽  
Correlation Coefficients ◽  
Ammonia Solution ◽  
Alcohol Concentration ◽  
Molar Ratio ◽  
Nickel Ion ◽  
Nickel Ions ◽  
Thiourea Dioxide ◽  
Kinetics Of ◽  
Sulfoxylic Acid

A stoichiometric mechanism for thiourea dioxide decomposition in water- ethanol-ammonia solution is proposed based on dependences of concentrations of thiourea dioxide over time and literature data. The concentration of thiourea dioxide was measured with iodometry, while the intermediates were qualitatively detected using the polarography. The set of the obtained data allows to consider that at low concentration of alcohol (approximately up to 0.1 molar ratio) the thiourea dioxide decomposition proceeds on the heterolytic mechanism with formation of sulfoxylic acid, and at high concentrations of alcohol – on homolytic mechanism with the formation of anion radicals. Rate constants for individual stages of heterolytic mechanism are obtained by mathematical modeling, presented a system of differential equations. Absolute errors of rate constants, correlation coefficients, and F-factors were also calculated. The linear correlation was found between the equilibrium constant logarithm of the decay stage of thiourea dioxide and the inverse value of the dielectric constant of water-alcohol solutions. The kinetics of reduction of nickel ions with thiourea dioxide in an aqueous ammonia solution with ethanol additives was also studied. Сoncentration of nickel ions was determined using complexometric titration. Obtained kinetic data showed that at alcohol concentrations of 0.13 molar ratio and more, reaction kinetics is described by a first-order equation. At lower ethanol concentrations, a fractional order is observed on the concentration of nickel ions. A stoichiometric mechanism of this reaction is proposed due to sulfoxylic acid molecules with alcohol concentrations less than 0.1 molar ratio and due to radical ions with alcohol concentrations more than 0.1 molar ratio. Thus, the study of nickel ion reduction kinetics confirmed the conclusion about influence of alcohol concentration on the decomposition mechanism of thiourea dioxide.

Effect of surface active cations undergoing interfacial rearrangements on deposition type electrode reactions

1988 ◽  
Vol 53 (4) ◽  
pp. 732-742 ◽  
Author(s):  
Anastos Anastopoulos ◽  
Anastasia Christodoulou
Keyword(s):  
Rate Constants ◽  
Mercury Electrode ◽  
Size Ratio ◽  
Inhibition Mechanism ◽  
Electrode Reactions ◽  
Dropping Mercury Electrode ◽  
Surface Active ◽  
Activated Complex ◽  
Effect Of Surface

The influence of the adsorption of methyltriphenyl- and cyclopropyltriphenylphosphonium cations on simple deposition reactions of Cd2+ and Zn2+ at the dropping mercury electrode, is studied by polarographic techniques. The size parameters of the activated complex, r≠, and adsorbate particles, ri, are determined and discussed. It is shown that for substances undergoing interfacial rearrangements, i.e. condensation and reorientation, the values of the size ratio r≠/ri can hardly be correlated to independently determined values of r≠ and ri. Electrode coverages are related to formal rate constants and an elucidation of the inhibition mechanism is attempted.

Reduction and tensammetric pulse-polarographic currents of polynucleotides

1987 ◽  
Vol 52 (11) ◽  
pp. 2810-2818 ◽  
Author(s):  
Emil Paleček ◽  
František Jelen ◽  
Vladimír Vetterl
Keyword(s):  
Diagnostic Criteria ◽  
Pulse Width ◽  
Mercury Electrode ◽  
Pulse Amplitude ◽  
Single Strand ◽  
Pulse Polarography ◽  
Dropping Mercury Electrode ◽  
Adenylic Acid ◽  
Drop Time

The behaviour of electrochemically reducible single-strand polynucleotides (poly(adenylic acid)) and poly(cytidylic acid)) was studied by the differential (derivative) pulse polarography (DPP) and by other methods. Measurements were performed with the help of the dropping mercury electrode under various conditions specified by the pulse width, pulse amplitude, drop time etc. For the faradaic and tensammetric DPP peaks the diagnostic criteria were proposed which make it possible to classify even very small DPP peaks of double helical polynucleotides.

Determination of platinum in biological material by differential pulse polarography: Analysis in urine, plasma and tissue following sample combustion

1983 ◽  
Vol 48 (10) ◽  
pp. 2903-2908 ◽  
Author(s):  
Viktor Vrabec ◽  
Oldřich Vrána ◽  
Vladimír Kleinwächter
Keyword(s):  
Biological Material ◽  
Biological Fluid ◽  
Mercury Electrode ◽  
Differential Pulse ◽  
Differential Pulse Polarography ◽  
Linear Calibration ◽  
Catalytic Current ◽  
Pulse Polarography ◽  
Dropping Mercury Electrode

A method is described for determining total platinum content in urine, blood plasma and tissues of patients or experimental animals receiving cis-dichlorodiamineplatinum(II). The method is based on drying and combustion of the biological material in a muffle furnace. The product of the combustion is dissolved successively in aqua regia, hydrochloric acid and ethylenediamine. The resulting platinum-ethylenediamine complex yields a catalytic current at a dropping mercury electrode allowing to determine platinum by differential pulse polarography. Platinum levels of c. 50-1 000 ng per ml of the biological fluid or per 0.5 g of a tissue can readily be analyzed with a linear calibration.

The reduction of cobalt (II) ion in thiocyanate media by pulse polarography

1983 ◽  
Vol 48 (2) ◽  
pp. 544-549 ◽  
Author(s):  
Jorge Alfredo Bolzan ◽  
Robert Tokoro
Keyword(s):  
Mercury Electrode ◽  
Thiocyanate Complex ◽  
Catalytic Wave ◽  
Pulse Polarography ◽  
Dropping Mercury Electrode ◽  
Thiocyanate Concentration

The electroreduction of cobalt(II) in aqueous thiocyanate solutions at the dropping mercury electrode depends on the thiocyanate concentration. At [SCN-] = 0.3 mol/l the intermediate cobalt(I)-thiocyanate complex does exist electrokinetically and may be responsible for the appearance of a peaked catalytic wave. The predecessor species of this intermediate may be CoSCN+ and Co(SCN)2 in similarity to the behaviour of cobalt(II) with cyanide and azide ions.

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