Save Question 8 10 points A 10000 mL sample of hard water is

Save Question 8 (10 points) A 100.00 mL sample of hard water is to be titrated with 003139 M EDTA solution. A small amount of Mg-sup>2t (that required 1.62 mL of EDTA to titrate as a blank solution) is added to the hard water sample. This sample requires 13.32 mL of EDTA to reach the endpoint. How many moles of Cacsup>2+

Solution

mL of EDTA consumed by Ca²⁺ = mL of EDTA consumed by sample - mL of EDTA consumed by blank

                                                    = 13.32 mL - 1.62 mL

                                                    = 11.7 mL

Since 1 L = 1000 mL, 11.7 mL = 0.0117 L.

Moles of EDTA consumed by Ca²⁺ = molarity of EDTA x Volume of EDTA

= 0.03139 M x 0.0117 L

= 0.000367263 mol

Since EDTA and Ca²⁺ reacts 1:1 mole ratio,

the number of moles of Ca²⁺ in the hard water is 0.000367263mol.