Hardness Test Procedure for Water | Titration Method

You are currently viewing Hardness Test Procedure for Water | Titration Method

Hardness Test apparatus Requirements

  • Take 50 ml water sample
  • Conical flask 250 ml
  • Ammonia buffer solution: Dissolve 67.5 gm of ammonium chloride in 570 ml of ammonium hydroxide and dilute to one liter with deionised water.
  • Eriochrome Black -T indicator: Dissolve 0.5 gm of EBT in 10 ml Methanol & makeup to 100 ml
  • 0.02 N EDTA Solution: Take 3.723 gm of EDTA in the 1 lit. volumetric flask. Add DM water to 1000 ml mark in the flask.
  • Inhibitor for Heavy metals: Dissolve 5.0 g sodium sulfide (Na2S.9H2O) in 100 ml Distilled water.

Hardness Test Procedure

  • Take 50 ml Sample in a 250 ml conical flask.
  • Add 2 – 4 ml Ammonia Buffer and mix by stirring.
  • Add 3-4 drop EBT indicator.
  • Titrate against 0.02 N EDTA solution.
  • Check for the end point – Wine Red to Blue color.

Water Hardness Test Video guide

Video Credit: NCTEL

Hardness Calculation:

Total Hardness as CaCO3 (ppm) =  (TV X Normality of EDTA X 1000 X 50)/ Sample volume

Note: If heavy metals like Iron are high, add 1 ml of inhibitor solution in hardness
If alkalinity is more than 300ppm, take 50 ml water sample add 2ml HCl and boil for
half an hour and proceed for hardness analysis.

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