工业用六氟硅酸钠 游离酸度和六氟硅酸盐总含量的测定 滴定法

[中文适用范围]： 对于游离酸度，适用于含量（以 H2 SiF6 表示）等于或大于 0.1% (m/m) 的产品。 首先，在硝酸钾存在下，用溴百里酚蓝作为指示剂，用标准容量的氢氧化钠溶液滴定冰冷却的测试部分，测定游离酸含量，然后在接近沸点的温度下用标准容量的钠滴定氢氧化物溶液呈现永久蓝色。 [外文原描述]： With respect to the free acidity, applicable to products having contents, expressed as H2 SiF6 , equal to or more than 0,1 % (m/m). First, determination of the free acid contents by titration of an ice-cooled test portion with a standard volumetric sodium hydroxide solution in the presence of potassium nitrate and using bromothymol blue as indicator, then, followed by titration at near boiling temperature with standard volumetric sodium hydroxide solution to the appearance of a permanent blue colour.