SRPS H.B8.663:1992

Sodium hydroxide for industrial use — Determination of carbonates content — Titrimetric method

Scope

Applicable to products having contents, expressed as CO2 , of more than 0.01 % (m/m). Relates to a procduct containing neither sulphides nor chlorates or only sulphides or only chlorates. Preliminary test by boiling an acidified test sample in the presence of methyl orange and with a lead acetate paper strip in the vapour. The sulphides blacken the paper and chlorates delolourize the methyl orange. Products containing neither sulphides nor chlorates: liberation of carbon dioxide by acidification and heating. Entrainment in a flow of gas and absorption in an excess of barium hydroxide solution. Titration of the excess barium hydroxide solution with a standard volumetric hydrochloric acid solution in the presence of thymolphthalein as indicator.