Skip to content

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
test.
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.

Related Article:

Leave a Reply

Your email address will not be published.