Preparation of 0.5M Disodium Acetate Solution
Weigh 18.6 gm of disodium edetate in a 1000 ml volumetric flask add sufficient water to dissolve properly and dilute to 1000 ml with water. Standardize the solution in the following manner.
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Standrazition of 0.5 M Disodium Acetate Solution
Weigh approximately 0.2 g of calcium carbonate, previously dried at 110°C for 2 hours, cooled in a desiccator, transfer to a 250 ml conical flask, add 10 ml of water, and swirl to form a slurry.
Cover the flask with a watch glass and introduce 2 ml of dilute hydrochloric acid from a pipette. Swirl the content of the flask to dissolve the calcium carbonate properly.
Wash down the sides of the flask, the pipette's outer surface, and the watch glass with water to dilute 100 ml.
Add 15 ml of disodium edetate solution from a 50 ml burette 15 ml of 1 M sodium hydroxide solution and 300 mg hydroxyl naphthol blue, and continue the titration with 0.05M disodium edetate solution to a blue endpoint.
Each 1 ml of 0.05M disodium edetate is equivalent to 0.0050045gm of CaCO3
Calculation
Molarity = --------------------------------------
Volume consumed (ml) x 5.0045 × 100
ACCEPTANCE CRITERIA
1) The accuracy of the solution should be within ± 10% of the theoretical concentration.
2) RSD* of the triplicate results of standardization / re-standardization should not be more than 0.2 %.