Calomel Electrode normal

Fig. 6-10. Differential electric capacity, C, observed for mercury electrodes in dilute and concentrated solutions of sodium chloride (a) 0.01 M NaF, (b) 0.1 M NaF. = potential of zero charge Vnce = volt referred to the normal calomel electrode. [From Graham, 1954.]...

The aqueous saturated calomel electrode (SCE) is generally employed as the reference electrode though in a few cases as the normal calomel electrode (NCE), connected to the solution in the non-aqueous solvent by means of a salt bridge involving the latter solvent, in order to avoid contamination of the solution to be studied with water. Otherwise, an Ag/Ag+ or an Hg/Hg22+ electrode or... 

Figure 3.55, Double layer on mercury. Contribution of anions to the countercharge. Temperature 25°C. electrolyte concentration 0.1 M. Potentials with respect to a normal calomel electrode. (Redrawn from D.C. Grahame and B.A. Soderberg, J. Chem. Phys. 22 (19541 449.)...

W. M. Latimer, K. S. Pitzer, and C. M. Slansky, J. Ghent. Phys., 7,108 (1939). Free Energy of Hydration of Gaseous Ions and the Absolute Potential of the Normal Calomel Electrode. 

Reaction 1 represents any half-reaction whose Eo value is known (for example, the normal calomel electrode HgaCls2e - 2Hg° +2Cr, or the silver/silver chloride electrode AgCl + le - Ag + Cl )- Reaction 2 represents any other half-reaciion that is H ion dependent (e.g., H ... 

The normal calomel electrode (NCE), which employs a 1 N KCl solution instead of a saturated solution, has a smaller temperature coefficient [E = -t-0.280 — 2.4 x 10 x (t° — 25) versus NHE], but because it requires a standardized solution it is less convenient than the SCE. The potential change of SCE with temperature is less than 1 mV/degree and is of no importance for controlled potential electrolysis. 

This is the nearest approach we can make to a physical interpretation of P, le P is a quantity whose logarithm is proportional to the electrolytic potential of the electrode in question The following table gives the electrolytic potentials of a few electrodes, the values m the first column being referred to the normal calomel electrode as a zero electrode, the values of the second column referring to the normal hydrogen as a zero electrode... 

Electrode EP Normal Calomel" Electrode = o EP Normal Hydrogen Electrode = o... 

R Peteis [Zettsch physik Chem, 26, 193, 1895) was the first to systematically examine oxidation and reduction processes in such cells under definite conditions He used as one half of the element the normal calomel electrode, the value of which in absolute measure was taken to be o 56 volts, the mercury being positive with respect to the solution The cell might thus be diagrammatically represented— p I Fe+++ Hg2Cl2 I H... 

In this cell solution X" is the fluid the pH of which is desired, and the reference electrode is usually the tenth normal calomel electrode or the saturated calomel electrode. From the potential, Eof this cell at 1 Atm hydrogen pressure the pH may be computed from the formula, in which R = 2.3026 R,... 

Table III. Values of the Constant, eU for the Hydrogen Electrode and of Eg for the Quinhydrone Electrode for use in pH,Determinations at Various Temperatures with the 0.1 Normal Calomel Electrode...

In measurements of pH, instead of using a reference electrode, such as the tenth normal calomel electrode the Eo value of which is known, it is frequently convenient to establish the value of Eo in the equation... 

The potential of a hydrogen electrode in an acid solution is -0.465 V when measured against an SCE reference electrode. What would the potential be measured against a normal calomel electrode (1 M KCl) ... 

Dark-gray metallic powder hexagonal close-packed crystal lattice, d 9.062. mp 1497. E (aq) EH+ZEr —230 V (calc). Similar to the other rare earth metals, possesses two reduction potentials 1.770 and 1.875 volts (ref to the normal calomel electrode), Noddack, Brukl, Angew. Chem, 50, 362 (1937). Radioactivity induced by neutron bombardment Sugden. Nature 135,469 (1935) McLennan, Rann, ibid 136, 831 (1935). Spectrum Eder. Ber. Wien. Akad. [2aJ 124, 790 (1915) deGramont, Compt. Rend. 171, 1106 (1920) Mott, McDonald. Trans. Roy. Soc. Canada [3] 21, 230 (1927). 

Body-centered cubic crystal lattice d 5,244 mp 826°, Sol in liq ammonia. Shows two reduction potentials —0,710 and —2.510 v. (referred to a normal calomel electrode) Noddack, Brukl, Angew. Chem. 50, 362 (1937) gives two definite series of salts one in which the metal Is bivalent, and another in which it is trivalent. 

Colorless or faintly yellowish metal tarnishes in moist air Hexagonal close-packed structure at room temp d 7.886. mp 1312. E (aq) Gd3+/Gd —2-4 V (calc). Experimental reduction potentials (referred to a normal calomel electrode) -1.810, -1.955 V Noddack, Brukl, Angew Chem. 50, 362 (1937),... 

In Sorenson s work, the reference electrode was a 0.1 normal calomel electrode of the form... 

The half-wave potential in alcoholic sulfuric acid solution was found to be 0.714 (volt vs, normal calomel electrode), comparable to that... 

W. J. Muller found that there are certain current densities which vary with the time required to make the metal passive. W. Muthmann and F. Fraunberger found the electrode potential between chromium and A-KCl against the normal calomel electrode zero to be —0-63 volt for the most active metal, and -f-1 19 volt for the most passive. Fresh electrolytic chromium was found by B. Neumann to be strongly active. W. Muthmann and F. Fraunberger observed variations of the electrode potential with the same piece of metal. A piece 25 cms. long had a potential of —0-03 volt at one end, and -fO-03 at the other and when activated. 

For a 1 N solution of KCl, the electrode is called a normal calomel electrode (NCE) and E(NCE) = +0.280 V. The advantage of the SCE is that the potential does not change if some of the liquid evaporates from the electrode, because the Cl concentration does not change. Remember that samrated for the SCE refers to the KCl concentration, not to the mercurous chloride (calomel). 

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