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K_1和K_2的离解方程式如下: H_4SiO_4(?)H~++H_3SiO_4~- K_1=[H~+][H_3Si0_4~-]/[H_4Si0_4] (1) H_3SiO_4~-(?)H~++H_2SiO_4~()2- K_2=[H~+][H_2SiO_4~(2-)]/[H_3SiO_~-] (2) 由于在酸性溶液中有硅酸正离子H_5SiO_4~+的存在,故还应有另一个酸离解常数Ko,即 The dissociation constant of silicic acid is an important data to characterize the basic properties of silicic acid. Many previous work has been done, but due to the different methods and conditions, the data obtained are very inconsistent. In this work, the dissociation constants of all levels of silicic acid were determined by “N” curve method.The dissociation equation of K 1 and K 2 was as follows: H 4 SiO 4 (H) H ~ + + H 3SiO 4 ~ -K 1 = [H ~ +] [H 3 Si 0 4 H_3SiO_4 ~ -? H ~ + + H_2SiO_4 ~ () 2- K_2 = [H ~ +] [H_2SiO_4 ~ (2)] / [H_3SiO_ ~ -] Due to the existence of silicic acid positive ion H5SiO4 + in acid solution, there should be another acid dissociation constant Ko