Reference number
ISO 979:1974
ISO 979:1974
© ISO 2024
International Standard
ISO 979:1974
Sodium hydroxide for industrial use — Method of assay
Edition 1
1974-12
1974-12
ISO 979:1974
5417
Published
(Edition 1, 1974)
This publication was last reviewed and confirmed in 2023.
Therefore this version remains current.
Abstract
Method for determination of the titre; this is expressed conventionally as percentages by mass of NaOH, a) as total alkalinity and b) as caustic alkalinity, corresponding to the total alkalinity less the alkalinity due to carbonates. The principle consists in titration of the total alkalinity with standard volumetric hydrochloric acid solution in the presence of methyl orange as indicator. Calculation of the two amounts a) and b). The mass of carbon dioxide is determined by the method specified in ISO 3196. This method has also been approved by the IUPAC. - Cancels and replaces ISO Recommendation R 979-1969 of which it constitutes a technical revision.