Surface active agents — Preparation of water with known calcium hardness
NORMA vydána dne 5.4.1990
Označení normy: ISO 2174:1990-ed.3.0
Datum vydání normy: 5.4.1990
Počet stran: 4
Přibližná hmotnost: 12 g (0.03 liber)
Země: Mezinárodní technická norma
Kategorie: 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.