0.05 M EDTA Solution Preparation & Standardization

  • Dissolve 18.6 g of disodium ethylenediaminetetraacetate dihydrate (EDTA)(C10H14N2Na2O8·2H2O)13 in sufficient water to make 1000 mL, and store in a polyethylene container.

 Standardization of 0.05 EDTA Solution    

  • Weigh accurately about 200 mg of calcium carbonate14 transfer to a 400-mL beaker, add 10 mL of water, and swirl to form a slurry. 
  • Cover the beaker with a water glass and introduce 2 mL of hydrochloric acid (HCl, 3 :10) from a pipet inserted between the lip of the beaker and edge of the watch glass. 
  • Swirl contents of the beaker to dissolve the calcium carbonate. 
  • Wash down the sides of the beaker, the outer surface of the pipet, and the watch glass, and dilute to about 100 ml. While stirring the solution, preferably with a magnetic stirrer,
  • Add about 30 mL of the disodium ethylenediaminetetraacetate (EDTA) solution from a 50-mL burette. 
  • Add 15 mL of sodium hydroxide solution (NaOH, 40 g/L), 300 mg of hydroxy naphthol blue indicator, and continue the titration with the disodium ethylenediaminetetraacetate (EDTA) solution to a blue endpoint.


Calculate the molarity of the disodium ethylenediaminetetraacetate solution as follows:
        M = W / 100.09 * V 
           M = molarity of the disodium ethylenediaminetetraacetate solution,
           W = milligrams of CaCO3 in the sample of calcium carbonate taken, and
           V = milliliters of disodium ethylenediaminetetraacetate solution consumed.

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