This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1911 edition. Excerpt: ...E.M.F. set up, in the former case through the scarcity of the hydroxyl ions which makes the oxygen potential higher, and in ...Read MoreThis historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1911 edition. Excerpt: ...E.M.F. set up, in the former case through the scarcity of the hydroxyl ions which makes the oxygen potential higher, and in the latter case through the small number of the hydrogen ions, which raises the potential of the dissolving hydrogen. Thus, in the case of eerie and cerous sulphates in acid and in alkaline solutions the following values have been found for the single potential differences between a platinum plate and the solutions: --(a) 0-lMol.Ce(S04)2 + 0-05Mol.Ce, (SO4)a + 1-OMol. H2S04= +1-12 volt. (6) 0-15Ce02,0-05Ce203 in cone. K2C03 =-0-27 volt. It must be remembered that oxidation and reduction effects can only be regarded from a relative standpoint, just as in the case of the classification of metals in the electromotive series as positive or negative. The nature of the charge which a solution imparts to the immersed electrode will of course depend upon the. definition of the zero potential. Practical. The measurement of oxidation and reduction potentials is carried out in precisely the same manner as that used for the measurement of the single potential differences between metals and salt solutions. A platinum electrode, with well platinised surface forms one terminal, and is immersed in the solution which it is desired to investigate. This electrode is then connected with a suitable normal electrode, --either a calomel or a hydrogen electrode, the liquids in each being joined by means of a syphon, either directly or through any intermediate electrolyte. The electrode of the normal element forms the second terminal, and thus completes the cell. This is joined to a Lippmann electrometer, through a tapping key, and on to a slide wire potentiometer, which is adjusted until the electrometer indicates that the E.M.F. of the cellRead Less
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