Historical Review of the Hydrogen Electrode and the Calomel Cell in the Measurement of Hydrogen Ions

2009 ◽  
pp. 3-3-16
Author(s):  
C. N. Myers
Keyword(s):  
Historical Review ◽  
Hydrogen Ions ◽  
Hydrogen Electrode

scholarly journals The electrolytic behaviour of thin films. Part I.—Hydrogen

1928 ◽  
Vol 120 (784) ◽  
pp. 59-79 ◽  
Keyword(s):  
Metal Ion ◽  
Active Material ◽  
Atomic Layer ◽  
Surface Concentration ◽  
Hydrogen Ion ◽  
Hydrogen Ions ◽  
Hydrogen Atoms ◽  
Hydrogen Electrode ◽  
Electrode Processes ◽  
A Value

Few investigations have been made on the electrolytic behaviour of very thin metallic films. Whilst the work of Oberbeck and of Pring reveals the fact that a deposited layer of metal but a few atoms thick will produce an electrode possessing all the electromotive properties of the massive metal, yet information is lacking on the alteration of the electromotive force as these layers are built up. It might be anticipated that the behaviour of the electrode during the deposition of the first few layers would lead to interesting results, giving some insight into the mechanism of electrode processes and the range of action of forces of adhesion. In view of this it was considered a matter of some interest to investigate how far it might be possible to obtain data on the electrode potential and the rate of solution of the deposited atoms during the building up of the first atomic layer. The problem of metal ion deposition from aqueous solutions is complicated by the presence of other ions, such as the hydrogen ion, which can deposit simultaneously with the metal and affect the potential. For this reason the deposition of the hydrogen ion was first studied. It is well known that, in general, in order to bring about the continuous deposition of hydrogen ions at a metallic cathode, the potential must be maintained at a value considerably more negative than that of a reversible hydrogen electrode in the same electrolyte. The view most generally accepted is that this overpotential is due to an accumulation of electromotively active material on the electrode, and it has been suggested by various workers that it may consist of metallic hydrides, hydrogen atoms or negative hydrogen ions. With the exception of a paper by Knobel, little work has been done in determining the actual quantity of hydrogen accumulated on the cathode during the establishment of overpotential. Knobel, making the assumptions that the material was atomic hydrogen, that the relation between the solution pressure of the hydrogen P and the surface concentration of atoms C H is given by the relation P = k C H m , and that the potential is related to the pressure by the Nernst expression, calculated this quantity from the rate of growth of overpotential and found that for most metals it was considerably less than an atomic layer.

scholarly journals Hydrogen overvoltage and the reversible hydrogen electrode

1936 ◽  
Vol 157 (891) ◽  
pp. 423-433 ◽  
Keyword(s):  
Alternative Mechanism ◽  
Hydrogen Ions ◽  
Hydrogen Atoms ◽  
High Activation ◽  
Hydrogen Electrode ◽  
Potential Region ◽  
Reverse Transfer ◽  
Platinized Platinum ◽  
Hydrogen Overvoltage ◽  
Free Hydrogen

There are two fairly sharply contrasted methods by which hydrogen is liberated in electrolysis. At high overvoltage electrodes Tafel found that the current and electrode potential were related by i = ke - ε V/2 k T , a relation more recently confirmed by Bowden. These electrodes are not reversible and there is no evidence that the process H 2 → 2H + + 2ε can occur to any appreciable extent at potentials accessible to observation. Even at ordinary bright platinum, which has a fairly low overvoltage, Armstrong and Butler found that the ionization of hydrogen occurred to only a slight extent in the region between the reversible hydrogen potential and the potential at which oxygen begins to be formed. On the other hand, reversible hydrogen potentials have long been known at platinized platinum and similar electrodes, and it has been found that bright platinum and similar metals can be “activated” in various ways, whereby it is brought into a condition in which the reversible hydrogen potential can be realized. In this state the hydrogen overvoltage is low and at small displacements from the reversible value the potential varies linearly with the current, i. e ., V = V 0 — ki This relation can be accounted for on the assumption that there are two processes at the reversible electrode which are influenced exponentially by the potential, but in opposite directions. The theories of overvoltage which have been put forward have been concerned mainly with the behaviour of high overvoltage electrodes. In Gurney’s theory the potential determining process was the transfer of electrons from the metal to the hydrogen ions in the solution. As Gurney pointed out, this process is essentially irreversible, for the reverse transfer of electrons from either free hydrogen atoms or molecules cannot occur to an appreciable extent in the same potential region. Horiuti and Polanyi have suggested an alternative mechanism in which the primary process is the transference of hydrogen ions to adsorption positions at the surface of the metal, in the course of which neutralization occurs. This process may under some circumstances be reversible, but on the assump­tions made has a high activation energy of 20-30 k. cals.

The redox properties of Nicotinamide Methohalides

1953 ◽  
Vol 6 (4) ◽  
pp. 395 ◽  
Author(s):  
SJ Leach ◽  
JH Baxendale ◽  
MG Evans
Keyword(s):  
Sodium Dithionite ◽  
Potassium Ferricyanide ◽  
Cathodic Reduction ◽  
Hydrogen Ions ◽  
Hydrogen Electrode ◽  
Mercury Surface ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Colloidal Platinum ◽  
Reversible Reduction

The reversible reduction of nicotinamide methiodide and methochloride has been studied using cathodic reduction at a mercury surface, sodium dithionite, hydrogen and colloidal platinum, and various leuco-dyes. The method of cathodic reduction was the most satisfactory. Polarography showed a 2-step reduction. Macro-reductions at a mercury surface suggested dimerization of the intermediate free radical. The behaviour of dihydromethylnicotinamide towards hydrogen ions, oxygen, iodine, potassium ferricyanide, ferric iron, and various dyes has been examined. Although it is not readily oxidized by oxygen it is capable of reducing most other systems with a higher Eo?:. Two methods of estimating the reduced compound are suggested and involve (a) the potentiometric titration of potassium ferricyanide at pH 9.1 and (b) the reduction and decolourization of 2.6-dichlorophenolindophenol at pH 4.7. The oxidation-reduction potential of nicotinamide methiodide has been measured by oxidative titration of the dihydro-compound at pH 9.1 and 30�0.01 �C and found to be -0.36 � 0.02 V against the normal hydrogen electrode. The titration curve does riot show a separation of the two reduction steps. Evidence is discussed for the production of both o- and p-dihydromethylnicotinamide during reduction.

A Historical Review of Complex Regional Pain Syndrome in the “Guides Library”

2009 ◽  
Vol 14 (6) ◽  
pp. 1-9
Author(s):  
Robert J. Barth
Keyword(s):  
Differential Diagnosis ◽  
Complex Regional Pain Syndrome ◽  
Reflex Sympathetic Dystrophy ◽  
International Association ◽  
Historical Review ◽  
Pain Syndrome ◽  
Sixth Edition

Abstract Complex regional pain syndrome (CRPS) is a controversial, ambiguous, unreliable, and unvalidated concept that, for these very reasons, has been justifiably ignored in the “AMA Guides Library” that includes the AMAGuides to the Evaluation of Permanent Impairment (AMA Guides), the AMA Guides Newsletter, and other publications in this suite. But because of the surge of CRPS-related medicolegal claims and the mission of the AMA Guides to assist those who adjudicate such claims, a discussion of CRPS is warranted, especially because of what some believe to be confusing recommendations regarding causation. In 1994, the International Association for the Study of Pain (IASP) introduced a newly invented concept, CRPS, to replace the concepts of reflex sympathetic dystrophy (replaced by CRPS I) and causalgia (replaced by CRPS II). An article in the November/December 1997 issue of The Guides Newsletter introduced CRPS and presciently recommended that evaluators avoid the IASP protocol in favor of extensive differential diagnosis based on objective findings. A series of articles in The Guides Newsletter in 2006 extensively discussed the shortcomings of CRPS. The AMA Guides, Sixth Edition, notes that the inherent lack of injury-relatedness for the nonvalidated concept of CRPS creates a dilemma for impairment evaluators. Focusing on impairment evaluation and not on injury-relatedness would greatly simplify use of the AMA Guides.

Historical Review of Psychology and Segregation

2008 ◽  
Author(s):  
Raychel C. Muenke ◽  
Valerie Weed
Keyword(s):  
Historical Review
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