Electro-chemistry. Part I, General theory / by R.A. Lehfeldt ... Including a chapter on the relation of chemical constitution to conductivity, by T.S. Moore.

Lehfeldt, R. A. (Robert Alfred), 1868-1927.

Date:: 1904

Credit: Electro-chemistry. Part I, General theory / by R.A. Lehfeldt ... Including a chapter on the relation of chemical constitution to conductivity, by T.S. Moore. Source: Wellcome Collection.

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$and cathode chambers is as follows (the middle chamber is always unchanged):— Anode Chamber. Discharge of i equiv. SO/', which reacts with water, forming i equiv. gaseous oxygen + i equiv. H', and reforming the SO/' [SO, + H20 = 2H- + SO/' + O] Export of i — x equiv. H‘ to middle chamber. Import of x equiv. SO/' from middle chamber. Net result:— | Net result:— Gain of x equiv. H- and the same of Loss of x equiv. II- and the same S04, i.e. of x equiv. II2S04. ■ of SO/', i.e. of a; equiv. 1I2S04. In this case, too, the anode solution increases in strength at the expense of the cathode; the change is easily followed by titration. It is found that about o'i9 equivalents of acid migrate for each faraday, so that x = o'19. On comparing the results of such experiments with the changes occurring at the electrodes, we find that quite different conditions regulate the flow of current in the two cases, although the total current must be the same at each part of the circuit. At the electrodes when there are several available ions, the current will be conveyed by that whose formation or discharge is the least difficult, i.e. involves the least expenditure of energy. The whole current may be, and often is, conveyed by a single kind of ion, so that it may be exclusively anionic or exclusively cationic. In the interior of the solution, on the other hand, all the ions present necessarily share in the current, and the share that each takes is determined merely by the amount of it present and by its specific mobility. This is true, not merely in considering the relation of anion to cation, but also with regard to the shares taken by the various ions of the same sign, if more than one be present; for the expressions of p. 21 still hold, however many ions may exist in the solution. Thus, in the case of copper sulphate, besides Cu there is H* in the liquid, although in very small proportion; hence a small part of the cationic current is carried by the hydrogen ions, and similarly a small part of the anionic by hydroxyl ions. In passing from an electrode to the interior, then, each Cathode Chamber. Discharge of 1 equiv. H\ Import of I — x equiv. H‘ from middle chamber. Export of x equiv. SO/' to middle chamber.$