Answer:
85.952 ml [tex]Zn^2^+[/tex] 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 [tex]CoSO_4[/tex] =[tex]\frac{Given mass }{molar mass}[/tex]
=[tex]\frac{1.817}{155}[/tex]
=0.01172
Molarity = [tex]\frac{no. of moles}{volume of solution}[/tex]
=[tex]\frac{0.01172}{20}[/tex]
=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 [tex](Zn^2^+)[/tex]
[tex]0.008419\times100ml=0.009795\times V2[/tex]
[tex]V2=\frac{0.008419\times100}{0.009795}[/tex]
V2 =85.952 ml
Therefore , 85.952 ml [tex]Zn^2^+[/tex] needed to titrate the excess complexing reagent .
