Materials & Reagents Required:

1. Tap water (100 mL)
2. Conical flask (250 mL)
3. Weighing balance
4. Dropper
5. Glass column
6. Measuring cylinder (10 mL)
7. Burette (50 mL)
8. Cation exchange resin
9. EDTA (0.01 M)
10. Ammonia buffer (pH 10)
11. EBT indicator
    

    Laboratory Procedure

    
    
    
    Repeat Step-5 and Step-6 three times.
    

    Procedure in laboratory
    

    
    

    Observation
    

    The color of soft water instantly changes into blue, while the hard tap water turns wine red when Eriochrome black T is added. The wine-red colored solution turns blue when titrated against the EDTA solution
    
    Formula: Total hardness of water mg/L = ml of EDTA used unboiled x 10³ / ml of sample