Part D - Determination of water hardness in unknown sample
Trial 1
Trial 2
Trial 3
Volume of unknown (mL)
25.00
25.00
25.00
Final Burette Reading (mL)
3.10
2.90
2.70
Initial Burette Reading (mL)
0.00
0.00
0.00
Volume of EDTA (mL)
3.10
2.90
2.70
Volume of EDTA used to titrate blank (mL)
0.50
0.90
0.05
Volume of EDTA required to titrate 25 mL of unknown sample (mL)
2.60
2.00
2.65
Moles of EDTA required to titrate 25 mL of unknown sample (moles)
2.65e-5
2.04e-5
2.70e-5
Moles of CaCO3 per 25 mL of unknown sample (moles)
2.65e-5
2.04e-5
2.70e-5
Weight of CaCO3 per 25 mL of unknown sample (g)
2.65e-3
2.04e-3
2.70e-3
Weight of CaCO3 per 106 mL of unknown sample (g)
106
81.6
108
Ppm of CaCO3 in unknown
106000
81600
108000
Average Ppm of CaCO3 in the unknown is 66733 +/- 31800 ppm
1. In reviewing the Ontario Drinking Water Standards, how does your unknown compare with the standard? How much calcium chloride or distilled water would be needed to be added to make your sample compliant? (2 marks)
2. Explain the process by which a water softener works, please include the regeneration process. (2 marks)