In hard water analysis, the end point is reached when 13.5 mL of 0.0913 M standardized EDTA has been added. Determine the water hardness in equivalence of CaCO3. That is, determine the mg CaCO3 per liter

13.5 mL x 0.0913M = millimoles EDTA = millimoles CaCO3.

g CaCO3 = mols x molar mass CaCO3.