Question

Need some help with this please

2 A 25,0 mL sample of tap water requires 5.5 mL of 0.00589 M EDTA solution to reach the endpoint. Express its hardness in mg/L CaCO3. According to the table on page 1, would this sample be considered "hard"?! 3. Go to http://water.usgs.gov/owg/hardness-alkalinity.html and find Dayton on the map. What is your expected result for hardness of untreated water in the Miami Valley? What would expect to be the result for the Seattle, WA, area?

Answer 1

Date: _1_1 2 Ca (as) + EDTA 0 ppt moles of EDTA - molarity & volume in litres = 0.00589m X 0.0055 L = 3.24 Xlo mol mass of Calog = - molar mass x moles = 100 g/ml x 3.24 x 10 ml - 3.24 x 10 9 = 32 32.4x100g - 32.4 mg in 25mL = 0.0252 this is present Ashe hardness = 32.4 mg = 12.96 mg/L 0.0252