How do you calculate hardness of water?
2017-05-23 9:32 pm
A 25.00mL sample of water buffered at a pH of 10 is titrated with 0.009885M EDTA using the Calmagite indicator. A volume of 6.82mL of EDTA is required. Determine the hardness of the water sample. so I know that hardness (ppm)= mCaCO3(mg)/ Vh2o (L).. but I'm nit really sure how to use that equation..pls help me thank you
回答 (1)
2017-05-23 10:43 pm
✔ 最佳答案
Ca 2+ reacts in 1:1 molar ratio with EDTAMol of EDTA in 6.82mL of 0.009885M EDTA solution = 6.82/1000* 0.009885M = 6.74*10^-5 mol EDTA
Therefore 25.00mL of water contain 6.74*10^-5 mol Ca2+
Mol Ca2+ in 1000mL = 1.0L water = 1000/25.00*6.74*10^-5 = 0.002697 mol Ca2+
OR: 0.002697 mol CaCO3 i8n 1.0L water
Molar mass CaCO3 = 100g/mol
Mass of CaCO3 in 1.0L water = 0.002697*100 = 0.2697g CaCO3 in 1.0L water
0.2697g = 269.7mg CaCO3 in 1.0L water
Hardness = 269.7ppm CaCO3
收錄日期: 2021-04-24 00:26:09
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