(B) DETERMINATION OF THE TOTAL HARDNESS OF WATER
It is customary in practice to express the total hardness of water as parts per million (ppm.) Ca or ppm CaCO3.
PROCEDURE
• EDTA solution in A was diluted 10 times (pipetted 25 mL in a 250 mL volumetric flask diluted to the mark in a volumetric flask).
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• 50.00 mL of tap water was placed in a conical flask, 2 mL buffer solution and a spatula tip of Eriochrome Black T indicator were added and titrated with the diluted EDTA
the solution to the end-point.
• A series of titrations were performed. Choose the best three volumes and calculate the water hardness as ppm or mg/L CaCO3. (Remember the dilution factor)
• EDTA volumes: 16,14; 15,95; 17,00; 16,16; 16,95; 18,23 mL