Question

500 ml of a sample of water on EDTA titration with eriochrom black T as indicator consumes 18 ml of 0.045 M EDTA till the end point. calculate the hardness of water sample

Answer 1

Total hardness = (Volume of EDTA * Сn (EDTA) * Equivalent weight of CaCO3 * 1000) / volume of sample taken
0.045 M EDTA = 0.09 n EDTA
Total hardness = (18 * 0.09 * 50 * 1000) / 500 = 162 mg/L as CaCO3 equivalent