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Cr~(3+)的水解聚合作用很慢,聚合状态又很复杂,故至今系统研究极少。我们在Cr~(3+)浓度为0.0002—0.32M范围内用平衡静置pH法系统地研究了Cr~(3+)的水解聚合状态。结果表明,在低浓度区,水解多核产物的组成可表示为[Cr_3(OH)_4](OH)_n~((5-n)+)(n=1,2,3);在中等浓度区,产物为Cr[Cr(OH)_2]_n~((3+n)+)(n=1,2,3);在高浓度区,产物为Cr[Cr(OH)]_n~((3+2n)+)(n=1,2);而在中等浓度区和高浓度区之间有一过渡区,其水解产物为[Cr_3(OH)_3]~(6+)和[Cr_3(OH)_4]~(5+)。对同一种水解产物,在不同的Cr~(3+)浓度区和用不同的计算方法所得的水解常数互相符合得较好。根据所得水解常数作出了Cr~(3+)在水溶液中状态的优势面积图。
Cr ~ (3+) hydrolysis polymerization is very slow, the polymerization state is very complicated, so far little systematic research. We systematically studied the hydrolytic polymerization state of Cr 3+ in the range of 0.0002-0.32 M Cr 3+. The results show that the composition of hydrolyzed polynuclear products can be expressed as [Cr_3 (OH) _4] (OH) _n ~ (5-n) +) (n = 1,2,3) The product is Cr [Cr (OH) 2] _n ~ (3 + n) + (n = 1,2,3) (N = 1, 2) +) (n = 1, 2). However, there is a transitional zone between the medium and high concentration zones with the hydrolysis products of [Cr 3 OH 3] 6+ and [Cr 3 (OH) _4] ~ (5+). For the same hydrolysates, the hydrolysis constants obtained at different concentrations of Cr 3+ and calculated by different methods are in good agreement with each other. Based on the obtained hydrolysis constants, the dominant area of Cr 3+ in aqueous solution was obtained.