A General Relation of Electromotive Force to Equivalent Volume and Molecular Velocity of Substances

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Birmingham Philosophical Society, 1892 - Electromotive force - 138 pages
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Page 63 - ... of that force was produced by . the diluted liquid above that of the mean amount as calculated ^ from the separate amounts excited by the water and the ^ undiluted liquid, and that the gain was usually greatest with ^ acids, less with neutral salts, and least with alkalies ; and in a > subsequent research on " A Method of Measuring Loss of Energy Due to Chemical Union, &c.
Page 94 - ... solution, and the negative one in water. And in the second experiment of the pair, similar measurements were made with the negative metal in the solution of halogen, or acid, &c., and the positive one in water. In these experiments the electromotive force of the metal which was in water alone was disregarded, because the only change which was made during the measurements was in the other liquid. The following tables show the results...
Page 115 - Tables 86, 37, and 89, decreases of simple electromotive force occurred by liquefaction of magnesium, but not in a solution of KC1, by means of mercury, so also in Tables 41, 42, and 44, similar decreases occurred with that metal by dilution of its amalgam, excepting in the electrolyte mentioned. The effects of diluting the positive amalgam are usually more simple than those of diluting the electrolyte, because the latter affects the electromotive forces at both electrodes.
Page 104 - Acad. Sci., June 10, 1878. Chemical News, vol. xxxviii, p. 88.) But the above numbers further show that notwithstanding the adverse changes of thermal energy, the mean amount of electromotive force of cadmium in dilute hydrochloric acid was simultaneously increased 821 .2 per cent., thus proving that the influence of the thermal change upon that force was small in comparison with that of increased freedom of molecular motion due to liquefaction.
Page 136 - ... force by dilution. (See p. 83.) If, however, the temperature was sufficient to liquefy the positive metal, a sudden increase of electromotive force due to greater freedom of molecular motion occurred at the period of liquefaction. (See Phil. Mag., July, 1891, p. 29.) By dilution, the volume which a dissolved substance occupies in a liquid may be caused to increase until it is much larger than that normally filled by its vapour (see Expt.
Page 131 - ... increased the electromotive force and chemical energy of the substance diluted and...
Page 115 - Section 0, and need not be repeated ; and nearly all the remarks made on that section are applicable to this one. The effects of dilution of the positive amalgam upon the mean amount of electromotive force were substantially the same as those of liquefaction of the solid positive metal, but were less in amount. Thus, on comparing the percentage amount of gain of mean electromotive force obtained on liquefying 56 grains of cadmium by means of 5,544 grains of mercury in Experiment No. 153, Table...
Page 139 - Etc.," Phil. Mag., May-Dec., 1890). It might be supposed, as dilution of the positive metal or of the electrolyte diminishes the number of molecules of each of those substances which at any given moment strike each other per unit of surface, that this would diminish the actual electromotive force of the diluted substance ; but it was found that, although by diluting a solution of...
Page 98 - Gum 1-2271 volt. very different, and that the increase was often less or the decrease greater with electropositive metals giving large electromotive forces than with those giving smaller ones In several cases, for instance, iron in KCy, thallium, sodium, or nickel, &c., in KHO, the simple electromotive force was smaller in the solution than in water alone, and occasioned " losses
Page 102 - ... lessened ; the measurements, therefore, were in all cases made as quickly as possible after preparing the amalgams, and the latter were not disturbed during the measurements, because it altered the electromotive force. The dry amalgam of magnesium quickly formed the black suboxide of that metal. Several kinds of electrolytes, acid, neutral, and alkaline, were employed. The following tables show the results...

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