论文部分内容阅读
用络合滴定法测定钙、镁含量时,程氏建议用Calcon的锌盐作指示剂。Стюн-кель用酸性深蓝及酸性蓝,但均无显著优点。本文报告改用Beryllon Ⅱ(变色酸与H-酸偶联而成的偶氮染料)的结果和此指示剂的一些特点。 (一)探用新指示剂测定钙镁含量:Beryllon Ⅱ在微酸性中呈红色,而在pH=9.5—10.6时变为紫色。指示剂与钙及镁分别在pH=10.8—14.0,及9.6—14.0时生成蓝色络合物。因此,在pH=10.0时滴定,仍可得到由蓝色变为紫红色的明显终点。采用铬黑T或Beryllon Ⅱ作指示剂时,测定钙、镁的比较结果见表1(操作方法见
With complexometric titration of calcium and magnesium, Cheng recommends the use of Calcon’s zinc salt as an indicator. Стюн-кель with acid dark blue and acid blue, but no significant advantages. This article reports the results of using Beryllon II (an azo dye coupled with chromotropic acid and H-acid) and some of the characteristics of this indicator. (A) Determination of calcium and magnesium content with a new indicator: Beryllon Ⅱ reddish slightly acidic, and becomes purple when pH = 9.5-10.6. The indicator forms a blue complex with calcium and magnesium at pH = 10.8-14.0, and 9.6-14.0, respectively. Therefore, titration at pH = 10.0 still yielded a distinct end point from blue to fuchsia. The use of chrome black T or Beryllon Ⅱ as an indicator, the determination of calcium and magnesium in Table 1 (see the operation method