ON THE MECHANISM OF HYDROGEN ELECTRODE REACTION ON PLATINUM

Exchange reaction between pure deuterium and light water, P20, on platinum catalyst was conducted in acidic solutions and in pure water under a strong stirring, and the resultant exchange between deuterium and water, and extent of equilibration r = = [PD] / [PD] eq were observed, where [PD] is the concentration of PD in gas and [PD] eq that in the same gas brought to equilibrium of P2 +D2=2 PD. The r must be zero or unity according as the intermediate of the hydrogen electrode reaction is in equilibrium either with water as in the case of catalytic and electrochemical mechanisms or with hydrogen gas as in the case of the slow discharge mechanism; this propo· sition is subject to the conditions that the exchange reaction is governed by the appropriate heterogeneous reaction on the catalyst's surface but not by any transport process and that the equilibration P2 + D2 = 2 PD as well as the exchange reaction is effected solely by hydrogen electrode reaction but not by any other reaction, e.g. that of RIDEAL·ELEY mechanism, which concurrently results in the equilibration but not the exchange reaction by itself (called simply other reaction in what follows). The apparent heat of activation of the exchange reaction showed that the rate is purel