琼脂凝胶中形成铬酸铅周期性沉淀的机理研究

Mechanism of Periodic Presepitation in a Lead Chromate System Containing Agar-agar Gel

选择硝酸铅和铬酸钾作为相互扩散的反应物以形成铬酸铅在琼脂凝胶中的周期性沉淀．分别在光照和黑暗中对六种不同浓度的硝酸铅溶液进行了实验．根据实验现象对周期性沉淀的形成提出了可能的机理．认为光辐射可使铬酸铅部分电离，从而减慢了胶核成长速率，有利于汇聚成带．

The Pb(NO3)2 and K2CrO4 were chosen as the interdiffusing electrolytes forperiodic precipitation of PbCrO4 in an agar-agar gal. Six series of experdrients in whichthe concentration of Pb(NO3)2 solution was different from another were performed tmderintalnation and dark respectively. on the basis of phenomena of the experiments a pos sible mechanism of formation of periodic precipitation was reported. It was consideredthat the PbCrO4 was dissociated partly under the light radiation, the growth velocity ofthe colloid nuclei was increased, and therefore presence of light was favorable for patternformation.