A 0.512 g sample of CaCO3 is dissolved in 12 M HCl and the mixture is diluted to 250 mL. A small amount of MgCl2 solution is added to a 25 mL aliquot of the solution., and the mixture is titrated with (ethylenediaminetetraacetic acid) EDTA to the Eriachrome Black T (with MgCl2 is used as indicator) end point. The mixed solution requires 28.55 mL of the EDTA solution to reach the end point. A similar amount of MgCl2 solution requires 2.60 mL to reach the endpoint. A 100-mL sample of hard water is titrated with 22.4 mL of the EDTA solution created above. The same amount of MgCl2 is added as previously and the total volume of EDTA solution required is 22.44 mL. a) Assume all of the Ca2+ in the water comes from CaCO3. How many moles of CaCO3 are in 1 L of water? How many grams of CaCO3 are in 1 L of water? c) If 1 ppm CaCO3 = 1 mg/liter, what is the water hardness in ppm CaCO3 ?
A 0.512 g sample of CaCO3 is dissolved in 12 M HCl and the mixture is diluted to 250 mL. A small amount of MgCl2 solution is added to a 25 mL aliquot of the solution., and the mixture is titrated with (ethylenediaminetetraacetic acid) EDTA to the Eriachrome Black T (with MgCl2 is used as indicator) end point. The mixed solution requires 28.55 mL of the EDTA solution to reach the end point. A similar amount of MgCl2 solution requires 2.60 mL to reach the endpoint.
A 100-mL sample of hard water is titrated with 22.4 mL of the EDTA solution created above. The same amount of MgCl2 is added as previously and the total volume of EDTA solution required is 22.44 mL.
a) Assume all of the Ca2+ in the water comes from CaCO3.
How many moles of CaCO3 are in 1 L of water?
How many grams of CaCO3 are in 1 L of water?
c) If 1 ppm CaCO3 = 1 mg/liter, what is the water hardness in ppm CaCO3 ?
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