5.1. 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
    

    5.2. Laboratory Procedure

    
    
    
    Repeat Step-5 and Step-6 three times.
    

    5.3. Procedure in laboratory
    

    
    

    5.4 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
    

    5.5. Sample Data and Analysis
    

    5.5.1 Titration of hard water (normal tap water)
    

    
    Therefore, the average volume of EDTA needed is 9.3 mL.
    

    5.5.2 Calculation
    

    
    

    Analysis
    

    From the experiment, the hardness of tap water is found to be 93 ppm