Sodium hexafluorosilicate for industrial use — Determination of free acidity and total hexafluorosilicate content — Titrimetric method
NORMA vydaná dňa 1.3.1977
Označenie normy: ISO 4281:1977
Dátum vydania normy: 1.3.1977
Počet strán: 2
Približná hmotnosť: 6 g (0.01 libier)
Krajina: Medzinárodná technická norma
Kategória: Technické normy ISO
Description / Abstract: 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.