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I. Chronoamperometry and chronopotentiometry with unshielded, circular, planar electrodes. II. Applications of potential step chronocoulometry. III. Faradaic integration of diffuse double layer

Citation

Lingane, Peter James (1966) I. Chronoamperometry and chronopotentiometry with unshielded, circular, planar electrodes. II. Applications of potential step chronocoulometry. III. Faradaic integration of diffuse double layer. Dissertation (Ph.D.), California Institute of Technology. http://resolver.caltech.edu/CaltechTHESIS:11292011-085122446

Abstract

The first portion of this dissertation demonstrates both theoretically and experimentally that the chronoamperometric and chronopotentiometric constants obtained with unshielded, circular, planar electrodes are of the form

[...]

Higher order terms appear to be unimportant under normal experimental conditions (1,2).

The second portion presents the results of detailed calculations of "working tables" for double potential step chronocoulometry applied to the study of first-order chemical reactions of the form

[...]

where Y is non-electroactive. The double potential step chronocoulometric technique is applied to the study of the Ti(m)-hydroxylamine reaction (3) and it is shown that the previously determined value of the Arrhenius energy is inexplicably too small by a factor of two. A new technique for the estimation of the electrochemical parameters of electrode reactions from potential step data is developed (4) and it is shown that this technique eliminates the need for a short- or a long-time approximation.

The final sections discuss the results of chronopotentiometric and chronocoulometric experiments conducted in the presence of "insufficient" supporting electrolyte. It is shown that the observed chronopotentiometric E-t curves should be distorted by the sum of "liquid junction" and "iR_u" voltages. Doublet chronopotentiometric waves are observed for the reduction of certain transition metals. The measured chronopotentiometric constant increases at high current densities and this is interpreted in terms of the reaction of electroactive material in the diffuse layer. It is shown that the residual uncompensated resistance in solutions of low concentrations of supporting electrolyte introduces sufficiently large uncertainties in the potential step chrono- coulometric Q-t^½ intercepts as to invalidate this technique under these conditions.

A least-squares analysis of chronopotentiometric data for the estimation of adsorption statistics according to three common models is described and the listing of a suitable Fortran IV computer program is included.

Extensive tables are calculated for the amount of a doubly charged ion in the diffuse double layer as a function of the concentration of the singly charged indifferent electrolyte.

(1) Anal. Chem., 36, 1723 (1964).

(2) J. Phys. Chem. , 68, 3821 (1964).

(3) J. Electroanal. Chem., in press (1966).

(4) J. Electroanal. Chem. , 10, 284 (1965).

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Chemistry
Degree Grantor:California Institute of Technology
Division:Chemistry and Chemical Engineering
Major Option:Chemistry
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Anson, Fred C.
Thesis Committee:
  • Unknown, Unknown
Defense Date:27 April 1966
Record Number:CaltechTHESIS:11292011-085122446
Persistent URL:http://resolver.caltech.edu/CaltechTHESIS:11292011-085122446
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:6740
Collection:CaltechTHESIS
Deposited By: John Wade
Deposited On:29 Nov 2011 17:34
Last Modified:26 Dec 2012 04:39

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