Hydrogen ions, generation

Figure 2.4 illustrates how the transformed equilibrium Gibbs free energy ArG ° varies with pH of the solution. Because of the hydrogen ion generated in the reference reaction of Equation (2.13), the reaction becomes more favorable as pH increases. Near pH of 7, the ArG ° is approximately —36 kJ mol-1. 

Lipsztajn et al. produced chlorine dioxide gas from a sodium ehlorate, sodium chloride, and hydrochloric acid electrolyte [82]. A cation exchange membrane separated the two electrode compartments. The hydrogen ions, generated by water electrolysis on a dimensionally stable anode, migrate through the eation exchange membrane to the cathode, where they react chemically with sodium chlorate and chloride ions to form chlorine dioxide. 

Strong and weak bases can be titrated with hydrogen ions generated at a platinum anode. 

Hydrogen ions generated at the surface of a platinum anode can be used for the coulometric titration of strong as well as weak bases ... 

Lipsztajn et. aL, [58] produced chlorine dioxide in the cathode compartment of an electrolytic cell using a three dimensional high surface area cathode. The cathodic section was separated from the anodic section by a cation exchange membrane. The hydrogen ions generated at the anode migrate to the cathode where they react with sodium chlorate along with chloride ions to form chlorine dioxide. The chlorine gas co-produced with the chlorine dioxide is reduced at the cathode to provide chloride ions. 

The silver bromide does not interfere with the neutralization reaction as would the hydrogen ions that are formed at most anodes. Both potentiometric and indicator end points can be used for these titrations. The problems associated with the estimation of the equivalence point are identical with those encountered in a conventional volumetric analysis. A real advantage to the coulometric method, however, is that interference by carbonate ion is far less troublesome. It is only necessary to eliminate carbon dioxide from the solution containing the analyte by aeration with a carbon dioxide free gas before beginning the analysis. The coulometric titration of strong and weak bases can be performed with hydrogen ions generated at a platinum anode. 

Geske (10) applied his theoretical observations to an experimental study of the electro-oxidation of tetraphenylborate ion and found an apparent increase in the number of faradays per mole with decreasing initial concentrations of electro-active material. By a consideration of the data obtained from current-time curves and solution analysis, it was possible to support a reaction scheme in which some of the tetraphenylborate ion is removed by reaction with hydrogen ions generated by interaction of one of the primary electrolysis products with the solvent. Reasonable agreement was found between the experimental findings and the predictions of the theoretical treatment given above. 

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