Faradaic impedance measurements of the ferrous/ferric citrate system

An examination of the ferrous/ferric citrate system has been made by the faradaic impedance technique. Determination of the reaction mechanism by the dependence of the rate on concentration has been attempted. The results have proved ambiguous in deciding whether the rate is controlled chemically or by the electron transfer stage. In addition, the negative dependence of the rate on iron(II) concentration has proved difficult to account for and a mechanism involving iron(IV) has been tentatively proposed.

Download Full-text

Faradaic Impedance Study of Mn(II) Reduction Mechanism in NaClO4 and NaCl Solutions on Mercury Electrode

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc20021589 ◽

2002 ◽

Vol 67 (11) ◽

pp. 1589-1595

Author(s):

Barbara Marczewska ◽

Andrzej Persona ◽

Marek Przegaliński

Keyword(s):

Electron Transfer ◽

Rate Constants ◽

Electrochemical Reaction ◽

Mercury Electrode ◽

Reduction Mechanism ◽

True Rate ◽

Faradaic Impedance ◽

Impedance Measurements ◽

Order Of Magnitude ◽

Adsorptive Properties

The electrochemical reaction of the Mn(II)/Mn(Hg) system on mercury electrode was studied in 1 M NaClO4 and 1 M NaCl as supporting electrolytes of different complexing and adsorptive properties. The impedance measurements confirmed the two-stage electroreduction of the Mn(II) in investigated solutions. Both the apparent and the true rate constants of the second electron transfer in both supporting electrolytes are lower by one order of magnitude than the rate constant of the first electron transfer. Similar values of corrected rate constants in both electrolytes suggest the similarity in mechanism of the Mn(II) electroreduction.

Download Full-text

Theory of Faradaic distortion: Equation for the second-harmonic current

Australian Journal of Chemistry ◽

10.1071/ch9640715 ◽

1964 ◽

Vol 17 (7) ◽

pp. 715 ◽

Cited By ~ 20

Author(s):

HH Bauer

Keyword(s):

Voltage Drop ◽

Second Harmonic ◽

Electrochemical Reactions ◽

Harmonic Current ◽

Faradaic Impedance ◽

Impedance Measurements ◽

Current Voltage ◽

Concentration Changes ◽

Harmonic Components

An equation is derived for the magnitude of the second-harmonic current under ax. polarographic conditions. It is shown that the concentration changes of the depolarizer at the electrode surface do not contain second-harmonic components. The theory permits determination of the rate constant and transfer coefficient, for processes of greater speed than are amenable to elucidation by faradaic-impedance measurements. Furthermore, the major experimental difficulties in faradaic-impedance studies (base current, voltage drop in the series resistances) are virtually absent in second-harmonic work. Second-harmonic studies also promise to be advantageous in the elucidation of adsorption effects in electrochemical reactions.

Download Full-text

Faculty Opinions recommendation of The roles of coenzyme A in the pyruvate:ferredoxin oxidoreductase reaction mechanism: rate enhancement of electron transfer from a radical intermediate to an iron-sulfur cluster.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1002479.109611 ◽

2002 ◽

Author(s):

Wolfgang Buckel

Keyword(s):

Electron Transfer ◽

Reaction Mechanism ◽

Coenzyme A ◽

Radical Intermediate ◽

Iron Sulfur Cluster ◽

Rate Enhancement ◽

Sulfur Cluster ◽

Iron Sulfur ◽

Pyruvate:Ferredoxin Oxidoreductase

Download Full-text

Determination of Complex Reaction Mechanisms

10.1093/oso/9780195178685.001.0001 ◽

2006 ◽

Author(s):

John Ross ◽

Igor Schreiber ◽

Marcel O. Vlad

Keyword(s):

Reaction Mechanism ◽

Reaction Mechanisms ◽

Reaction Pathway ◽

Chemical Species ◽

Rate Coefficients ◽

Chemical System ◽

Evolutionary Development ◽

Complex Reaction ◽

Oscillatory Reactions

In a chemical system with many chemical species several questions can be asked: what species react with other species: in what temporal order: and with what results? These questions have been asked for over one hundred years about simple and complex chemical systems, and the answers constitute the macroscopic reaction mechanism. In Determination of Complex Reaction Mechanisms authors John Ross, Igor Schreiber, and Marcel Vlad present several systematic approaches for obtaining information on the causal connectivity of chemical species, on correlations of chemical species, on the reaction pathway, and on the reaction mechanism. Basic pulse theory is demonstrated and tested in an experiment on glycolysis. In a second approach, measurements on time series of concentrations are used to construct correlation functions and a theory is developed which shows that from these functions information may be inferred on the reaction pathway, the reaction mechanism, and the centers of control in that mechanism. A third approach is based on application of genetic algorithm methods to the study of the evolutionary development of a reaction mechanism, to the attainment given goals in a mechanism, and to the determination of a reaction mechanism and rate coefficients by comparison with experiment. Responses of non-linear systems to pulses or other perturbations are analyzed, and mechanisms of oscillatory reactions are presented in detail. The concluding chapters give an introduction to bioinformatics and statistical methods for determining reaction mechanisms.

Download Full-text

The application of impedance measurements for the determination of the probability of the course of corrosion processes

Corrosion Science ◽

10.1016/s0010-938x(97)00011-5 ◽

1997 ◽

Vol 39 (6) ◽

pp. 1087-1092 ◽

Cited By ~ 5

Author(s):

K. Darowicki

Keyword(s):

Impedance Measurements

Download Full-text

REACTION MECHANISM OF ONE-POT SYNTHESIS OF POLYCYCLIC QUINONES —DIRECT EVIDENCE OF PHOTO-INDUCED ELECTRON TRANSFER PROCESS

Chemistry Letters ◽

10.1246/cl.1983.843 ◽

1983 ◽

Vol 12 (6) ◽

pp. 843-844 ◽

Cited By ~ 1

Author(s):

Kazuhiro Maruyama ◽

Seiji Tai ◽

Tetsuo Otsuki

Keyword(s):

Electron Transfer ◽

Reaction Mechanism ◽

Transfer Process ◽

Direct Evidence ◽

Electron Transfer Process ◽

One Pot ◽

One Pot Synthesis ◽

Photo Induced Electron Transfer

Download Full-text

Atomic absorption spectrometry of cobalt in the presence of chelating agents

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19803313 ◽

1980 ◽

Vol 45 (12) ◽

pp. 3313-3319 ◽

Cited By ~ 4

Author(s):

Josef Komárek ◽

Dalibor Kolčava ◽

Lumír Sommer

Keyword(s):

Reaction Mechanism ◽

Atomic Absorption Spectrometry ◽

Atomic Absorption ◽

Chelating Agents ◽

Absorption Spectrometry ◽

Donor Atom ◽

Optimum Conditions

The effect of chelating agents on the determination of cobalt in various flames, in a graphite cuvette and tantalum boat was studied considering the expected reaction mechanism of the atomization of cobalt and the reagent donor atom. A marked increase in the sensitivity of the determination of cobalt was observed in the presence of 1-(2-pyridylazo)-2-naphthol, pyrrolidinedithiocarboxylate, diethyldithiocarbamate, 8-mercaptoquinoline, 8-hydroxyquinoline and thenoyltrifluoroacetone for atomization from a tantalum boat. The optimum conditions for the determination of cobalt in the presence of 1-(2-pyridylazo)-1-naphthol are given.

Download Full-text