A study of instantaneous current-time curves obtained during the discharge of divalent cobalt at the dropping mercury electrode

1967 ◽  
Vol 32 (10) ◽  
pp. 3500-3509 ◽  
Author(s):  
E. T. Verdier
Keyword(s):  
Mercury Electrode ◽  
Current Time ◽  
Dropping Mercury Electrode ◽  
Instantaneous Current ◽  
Divalent Cobalt

Polarographic current-time curves and the Ilkovic Equation.

1958 ◽  
Vol 11 (3) ◽  
pp. 271 ◽  
Author(s):  
HA McKenzie
Keyword(s):  
Mercury Electrode ◽  
Potassium Nitrate ◽  
Current Time ◽  
Current Voltage ◽  
Modified Equations ◽  
Dropping Mercury Electrode ◽  
Instantaneous Current ◽  
Average Current ◽  
The One ◽  
Oxygen Measurements

The Ilkovic equation for the limiting diffusion current obtained with a dropping mercury electrode predicts that the instantaneous current grows during the life of the mercury drop as the one-sixth power of the time, and that the ratio of the instantaneous current at the end of the drop life (the maximum current) to the average current is 1.17. McKenzie (1948) showed in a preliminary study that these relations are not obeyed. The present paper is concerned with a more detailed study of current-time curves for cadmium(II), lead(II), and thallium(I) ions and oxygen. Measurements are made both in the presence and absence of maximum suppressor (gelatin) in two supporting electrolytes (potassium chloride and potassium nitrate). It is found that the rate of growth of the instantaneous current is not in accordance with the Ilkovic equation. Also, it does not accurately follow the modified equations, such as the Lingane-Loveridge equation, particularly during the early stages of drop life. The ratio of maximum to average current varies for the different electroactive substances, but in all cases examined 1.23<imax./iav.<1.30. An interesting observation is also made on the current-time curves for cadmium(II) in potassium nitrate in the presence of gelatin. At pH values appreciably below the isoelectric point (?pH 5) the current-time curves and the current-voltage curves are distorted. The implications of these results in the measurement of polarographic waves, both in theoretical and analytical applications, are discussed.

Current-time characteristics of the rapidly dropping mercury electrode

1960 ◽  
Vol 23 ◽  
pp. 585-591 ◽  
Author(s):  
Reita Tamamushi ◽  
Sunao Momiyama ◽  
Nobuyuki Tanaka
Keyword(s):  
Mercury Electrode ◽  
Current Time ◽  
Dropping Mercury Electrode

Polarography of azobenzene and its p-sulphonic acids

1964 ◽  
Vol 17 (10) ◽  
pp. 1085 ◽  
Author(s):  
TM Florence ◽  
YJ Farrar
Keyword(s):  
Ph Effect ◽  
Aqueous Media ◽  
Mercury Electrode ◽  
Electrode Reaction ◽  
Ammonium Ions ◽  
Current Time ◽  
Electrode Processes ◽  
Ph Values ◽  
Strong Adsorption ◽  
Dropping Mercury Electrode

The behaviour at the dropping mercury electrode of trans-azobenzene and its p-sulphonic acids has been studied by several techniques including d.c., a.c., single sweep, and Kalousek polarography. Current-potential curves recorded at the streaming mercury electrode provided information on the reversibility of the electrode processes, while current-time and electrocapillary curves aided in elucidating the effects of adsorption. The results show that the rate of the electrode reaction of the azo-hydrazo couple is dependent on pH, the minimum rate occurring near pH 9 for azobenzene-4-sulphonic acid in aqueous media. At very low and high pH values, the couple approaches full reversibility at the dropping mercury electrode. This pH effect is apparently due to strong adsorption of both the azo and hydrazo derivatives near the potential of the electrocapillary maximum. Ammonium ions associate with azobenzene-4-sulphonate, and improve the reversibility in intermediate pH regions.

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