【摘要】 <正> 硅酸的离解常数是表征硅酸基本性质的重要数据,前人已有不少工作,但由于测定的方法和条件不同,所得数据很不一致。本工作用“N”曲线法测求了硅酸的各级离解常数. 硅酸的K₁和K₂的离解方程式如下: H₄SiO₄（?）H⁺+H₃SiO₄^- K₁=[H⁺][H₃Si0₄^-]/[H₄Si0₄] （1） H₃SiO₄^-（?）H⁺+H₂SiO₄2- K₂=[H⁺][H₂SiO₄^2-]/[H₃SiO_<sup>-] （2） 由于在酸性溶液中有硅酸正离子H₅SiO₄⁺的存在,故还应有另一个酸离解常数Ko,即更多还原

【Abstract】 Monosilicic acid of sufficient concentration readily sets into a gel. When the logarithm of gelation time (lg t) is plotted against the initial pH of the acid solution in a wide enough range, a N-shaped curve would result. According to the theory of polymerization of silicic acid proposed by us previously, the pH values at the maximum and minimum points of the curve bear inherent relations with the dissociation constants of the various species of the monosilicic acid which are involved in the polymerzation process. With different acidifying agents and salt concentrations, the maximum and minimum points of the lg t-pH curve vary somewhat and the dissociation constants derived therefrom are not constant. In the present study, with a definite acidifying agent, when the total salt concentration is maintained constant, the maximum and minimum, points of the lg t-pH curve of gelation have been found constant and the disscoiation constants calculated therefrom show consistent values.更多还原