The effect of chloride ions on the electrochemical behaviour of nickel at mercury electrodes

摘要: Summary The behaviour of Ni(II) and Ni(0) has been studied in aqueous solutions mixtures LiCl LiNO 3 at chloride concentrations up to 14 M , by using combined techniques (d.c. pulse polarography, double potential step chronocoulometry chronopotentiometry). kinetics the reduction process is controlled free water contents. At constant activity, reaction orders, with respect bulk concentration, are +1. high concentrations, Tafel plots yield two straight lines respective slopes 43 170 mV. data explained assuming that chemical [Ni(H 2 O) 6 ] + Cl − ⇌[Ni(H 5 Cl] H O precedes bielectronic apparent values transfer coefficients α → 1 = 0.35 ← 0.4 . Reoxidation cathodically generated gives slopes, which characterized an about 0.4, a very small effect order These facts rate determining consists chloride-assisted electron abstraction Ni+Cl - e →NiCl. A mechanism proposed, ion acting as catalyst Ni +Cl ⇌NiCl slow charge process.