Page 108 - QRedition5.0 062021

Quality Requirements Edition 5.0 European Enamel Association

Determination of the total hardness Test report
Take 100 ml of the water to be tested and mix it with a few drops ammonia and one indicator To be mentioned are:
buffer tablet. Titrate with Complexon-A from red violet via grey till the colour changes into Kind and origin of samples
green. Place and date of test
Water temperature
ml consumption of Complexon X 5.6 = German hardness pH-value and conductivity of water
o
Total-, Calcium- and Magnesium hardness

Determination of the calcium and magnesium hardness

Mix 100 ml of the water to be tested with 4 ml potash lye and 5 - 10 drops of 0.4%
Calcon carboxylic acid. In presence of Ca-ions the solution is wine red. Titrate this with
Complexon-C-solution till the colour changes into net blue.

ml consumption of Complexon X 2.4 = German calcium hardness
o

The magnesium hardness is calculated :

Magnesium hardness = total hardness - calcium hardness

Required reagents

Complexon A
Indicator buffer tablets for the determination of hardness
Ammonia solution p.a. (about 25%)

Complexon C
Potash lye

50 g solid potassium hydroxide to be dissolved in
50 ml distilled water
!!! wear protective glasses !!!

Calcon carboxylic acid solution
0.4 g Calcon carboxylic acid to be dissolved in 100 ml methanol

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