Question

A solution contains 1.817 mg of CoSO4 (155.0 grams/mole) per mL. Calculate the volume (in mL) of 0.009795 M Zn2 needed to titrate the excess complexing reagent after the addition of 70.00 mL of 0.009005 M EDTA to a 20.00 mL aliquot of the Co2 solution.

Answer 1

Answer:

85.952 ml $Zn^2^+$  needed to titrate the excess complexing reagent .

Explanation:

Lets calculate

After addition of 80 ml of EDTA the solution becomes = 20 + 70 = 90 ml

As the number of moles of $CoSO_4$ =$\frac{Given mass }{molar mass}$

                                                       =$\frac{1.817}{155}$

                                                          =0.01172

Molarity = $\frac{no. of moles}{volume of solution}$

           =$\frac{0.01172}{20}$

        =0.000586 moles

Excess of EDTA = concentration of EDTA - concentration of CoSO4

                            = 0.009005 - 0.000586

                           = 0.008419 M

As M1V1 ( Excess of EDTA ) = M2V2 $(Zn^2^+)$

           $0.008419\times100ml=0.009795\times V2$

           $V2=\frac{0.008419\times100}{0.009795}$

             V2 =85.952 ml

Therefore , 85.952 ml $Zn^2^+$ needed to titrate the excess complexing reagent .