Prepare 0.05 mol/l EDTA Solution

General Information:

      One liter of this solution contains 18.612 g of disodium
ethylenediaminetetraacetate (C10H14N2Na2O8ŋ2H2O, molecular weight: 372.24).

Procedure:
     Weigh 18.7 g of disodium ethylenediaminetetraacetate, and dissolve in
freshly boiled and cooled water to make 1,000 ml.

Standardization:   

     Measure exactly 20 ml of 0.05 mol/l EDTA, add 2 ml of ammoniaʵammonium chloride buffer (pH 10.7) and water to make about 100 ml, and titrate with 0.025 mol/l zinc chloride (indicator: 5 drops of eriochrome black T TS).

                                       Volume (ml) of 0.025 mol/l zinc chloride consumed
   Normality factor =   ----------------------------------------------------
                                                 Volume (ml) of 0.05 mol/l EDTA ʷ 2