Page:Text-book of Electrochemistry.djvu/198

 From the numbers it can be seen that there is a good parallelism between the conductivities and the effects on the inversion. However, a more exact and thorough investiga- tion seemed advisable. I carried out an investigation {18) on this velocity of inversion, and it was afterwards extended by Palmaer {19), The result of these experiments was to show that at high dilution of the acids and constant sugar concentration the velocity of inversion is proportional to the concentration of the hydrogen ion present. At higher con- centrations deviations are observed of the same nature as those caused by the addition of neutral salts, the so-called action of salts (see p. 109). By addition of a laige quantity of acid^ the osmotic pressure of the cane sugar is increased so that the velocity of reaction p, instead of being proportional to the quantity m of hydrogen ion present, is regulated by the formula —

p = am + hm^.

The coefficient a is the same for all acids, i.e. it is inde- pendent of the nature of the anion ; h, on the other hand, is dependent on the anion, for this ion also acts so as to increase the osmotic pressure of the sugar, and all anions do not act to the same extent in this direction. The fact that a is the same for all acids evidently indicates that (at low concentra- tion) all hydrogen ions exert the same influence independently of the acid from which they are formed. It is therefore possible to calculate the velocity with which any acid can invert sugar if we know the velocity in the case of another acid, say hydi-ochloric acid, and the "salt action" of the various ions (which can be determined by other methods). The following table gives the reaction velocities for several concentrations of the acids. Under fi (observed) are given the numbers found by Ostwald.

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