Question

An aliquot containing 0.0005492 moles of Ca²⁺ is titrated to the Eriochrome Black T end point. A blank containing a small amount of measured Mg²⁺requires 2.94 mL of EDTA to reach the end point. The aliquot to which the same amount of Mg²⁺ is added requires 20.92 mL of EDTA solution to reach the end point. How many mL of EDTA are needed to titrate the Ca²⁺ in the aliquot?

Answer 1

mL of EDTA needed to titrate the Ca²⁺ = mL of EDTA needed for sample aliquot - mL of EDTA needed for blank

                                                              = 20.92 mL - 2.94 mL

                                                              = 17.98 mL