氯化铬—甲酸钠体系的电极反应

THE ELECTRODE REACTION OF CHROMIUM CHLORID ?SODIUM FORMATE SYSTEM

本文用单扫伏安法和循环伏安法研究了CrCl_3-HCOONa体系在电极上的反应。Cr(Ⅲ)水合离子在阴极电还原时往往生成Cr(Ⅱ)的中间离子,Cr(Ⅱ)易被还原成粉末状铬,而在CrCl_3—HCOONa体系中,配合物不易生成Cr(Ⅱ)中间离子,防上了粉末状铬的生成。另外,甲酸的氧化电位较低,在阳极优先被氧化,抑制了阳极上Cl_2和Cr(Ⅵ)的生成。

This paper deals with the reaction in the electrode of the CrCl3 -HCOONa system by means of the one-way ac. voltametrical method and the cyclic ac. voltametrical method. When the hydrated ion of Cr(III) is reduced in the cathode, usually intermediate ion of Cr(Ⅲ) may be created and Cr(Ⅱ) can be easily reduced to powdery chromium. However, in the system of CrCl3-HCOONa the coordination compounds can not be reduced to intermediate ion of Cr(Ⅱ) so easily. This prevents the creation of the dusty chromium. In addition, the oxidative potential of formic acid is so low that it is oxidated first in the anode and the production of Cl2 and Cr(Ⅵ) inhibited in the anode.