MISCELLANEOUS TECHNIQUES
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MISCELLANEOUS TECHNIQUES
MT 18 STANDARD WATERS
As for MT 18, CIPAC F, p. 59 together with:
18.5 Simplified method of preparing stock solutions
SCOPE The method may be used for preparing stock solutions, but in case of
dispute Standard Waters should be used which have been obtained by diluting
stock solutions prepared according to MT 18.1, CIPAC F, p.59.
REAGENTS
Calcium chloride anhydrous, purity at least 95 %. Dry for 2h at 105 °C before
use.
Magnesium chloride hexahydrate purity at least 99 %
Sodium hydrogen carbonate purity at least 99 %
STOCK SOLUTIONS
Solution I. 0.04 M Ca++ solution
Weigh accurately calcium chloride anhydrous (4.44 g) in 800 ml of distilled
or de-ionised water. Transfer quantitatively to a volumetric flask (1000 ml)
and make up to volume with distilled or de-ionised water. Store in a
polyethylene bottle for no longer than 30 days.
One ml of this solution when diluted to 1000 ml gives a water containing
4 ppm hardness expressed as calcium carbonate.
Solution II. 0.04 M Mg++ solution
Weigh accurately magnesium chloride hexahydrate (8.13 g) in 800 ml of
distilled or de-ionised water. Transfer quantitatively to a volumetric flask
(1000 ml) and make up to volume with distilled or de-ionised water. Store in
a polyethylene bottle for no longer than 30 days.
One ml of this solution when diluted to 1000 ml gives a water containing
4 ppm hardness expressed as calcium carbonate.
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MISCELLANEOUS TECHNIQUES
Solution III. 0.1 M sodium hydrogen carbonate solution
Weigh accurately sodium hydrogen carbonate (84.01 g) in 800 ml of distilled
or de-ionised water. Transfer quantitatively to a volumetric flask (1000 ml)
and make up to volume with distilled or de-ionised water. Store in a
polyethylene bottle for no longer than 30 days.
One ml of this solution when diluted to 1000 ml gives a water containing the
equivalent of 23 ppm of sodium.
Solution IV. 0.2 M Ca++ solution
Weigh accurately calcium chloride anhydrous (21.97 g) in 800 ml of distilled
or de-ionised water. Transfer quantitatively to a volumetric flask (1000 ml)
and make up to volume with distilled or de-ionised water. Store in a
polyethylene bottle for no longer than 30 days.
One ml of this solution when diluted to 1000 ml gives a water containing
20 ppm hardness expressed as calcium carbonate.
Solution V. 0.2 M Mg++ solution
Weigh accurately magnesium chloride hexahydrate (33.56 g) in 800 ml of
distilled or de-ionised water. Transfer quantitatively to a volumetric flask (1000
ml) and make up to volume with distilled or de-ionised water. Store in a
polyethylene bottle for no longer than 30 days.
One ml of this solution when diluted to 1000 ml gives a water containing
20 ppm hardness expressed as calcium carbonate.
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