Surface active agents — Preparation of water with known calcium hardness
NORMA vydaná dňa 5.4.1990
Označenie normy: ISO 2174:1990-ed.3.0
Dátum vydania normy: 5.4.1990
Počet strán: 4
Približná hmotnosť: 12 g (0.03 libier)
Krajina: Medzinárodná technická norma
Kategória: Technické normy ISO
Description / Abstract: A stock solution is prepared by dissolving an appropriate quantity of calcium chloride in water. The calcium content of this stock solution is determined by complexometric titration with the disodium salt of (ethylenedinitrilo)tetraacetic acid (EDTA) using a mixture of Mordant Black 11 (C.I. 14645) and methyl red as indicator. Dilute solutions of the hardness required are prepared by dilution of appropriate volumes of the stock solution.