Total Hardness :

Pipette 50 ml sample ( V2) into Erlenmeyer flask.

Add 1 ml of buffer solution ( mixture of EDTA , Magnesium Sulphate, Ammonium Chloride and Ammonium Hydroxide ).

Add 1 to 2 drops of EBT indicator.

Titrate using EDTA standard as titrant slowly with continuous stirring.

Continue titration until color changes from wine red to pale blue.

Record this volume of titrant used (V1).

Calcium & Magnesium Hardness :

Pipette 50 ml sample ( V4) into Erlenmeyer flask.

Add 2 ml of 1N Sodium Hydroxide tp produce pH of 12-13

Add 0.1 to 0.2 grams of Murexide indicator.

Titrate using EDTA standard as titrant slowly with continuous stirring.

Continue titration until color changes from kight pink to purple.

Record this volume of titrant used (V3).

Computation :

Total Hardness = [ V1 x (Conc of EDTA) x 100089 ] / V2

Calcium Hardness = [ V3 x (Conc of EDTA) x 40080 ] / V4

Magnesium Hardness = [ (V1 – V3) x (Conc of EDTA) x 24312 ] / V4


Related Posts :
Lead Content in Water
Alkalinity in Water
Acidity in Water
Chloride Content in Water
Sources , Occurences & Persistence of Factors affecting Physical & Chemical Aspect of Drinking Water