Hardness in groundwater is due to the presence of metal ions, primarily Mg2+and Ca2+. Hardness is generally reported asppm (mg/L) CaCO3or mmol/L Ca2+. To measure water hardness, a sample of groundwater is titrated with EDTA, a chelating agent, in the presence of the indicator eriochrome black T, symbolized here as In. Eriochrome black T, a weaker chelating agent than EDTA, is red in the presence of Ca2+and turns blue when Ca2+is removed. A 50.00-mL sample of groundwater is titrated with 0.0850M EDTA. Assume that Ca2+accounts for all of the hardness in the groundwater. Required:
If 10.10 mL of EDTA is required to titrate the 50.00-mL sample, what is the hardness of the groundwater in molarity Ca2+and in ppm CaCO3?