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The Role of Reactant Adsorption in the Electrode Reactions of Tl(2,2,2) + Cryptate Complexes at Mercury Electrodes
Author(s) -
Łobacz Marta,
Orlik Marek,
Stroka Jadwiga,
Galus Zbigniew
Publication year - 2002
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/1521-4109(200205)14:9<583::aid-elan583>3.0.co;2-c
Subject(s) - adsorption , electrode , thallium , chemistry , electrochemistry , dropping mercury electrode , kinetic energy , mercury (programming language) , reaction rate constant , analytical chemistry (journal) , standard electrode potential , inorganic chemistry , kinetics , organic chemistry , physics , quantum mechanics , computer science , programming language
Voltocoulometric, chronocoulometric and cyclic voltammetric studies of the electrode reaction of Tl(2,2,2) + cryptate at mercury electrodes are described. This process occurs via two parallel pathways – from the solution and from the adsorbed states which are energetically close. The kinetic and adsorption parameters of thallium(I) cryptate electroreduction were found by analysis of the normal pulse voltocoulometric curves recorded with a 1 ms delay after the application of the potential pulse. Such Q t−1 ‐ E dependences are characterized by a maximum that originates from the electroreduction of the adsorbed reactant. The model for numerical simulation of such curves was developed. Comparison of experimental and simulated curves allowed to determine apparent standard rate constant of Tl(2,2,2) + /Tl(Hg) couple as equal to 8×10 −3 cm s −1 , thus significantly lower than that for noncomplexed Tl + /Tl(Hg) system. The stability constant of the Tl(2,2,2) + complex (log K =6.70) and the surface coverage of the electrode by Tl + were determined.