Preparation and Standardization of 0.1 M Zinc Sulphate

Zinc Sulphate Solution Preparation

• Take about 100 ml of purified water in a cleaned and dried 1000 ml volumetric flask.
• Add about 28.8 gm of zinc sulfate with continues stirring. 
• Add more about 700 ml of purified water, mix and allow to cool to room temperature. 
• Make up the volume 1000 ml with purified water. Mix solution thoroughly. 
• Keep the solution for at least an hour and then carry out the standardization.

Zinc Sulphate Solution Standardization

Method I

• Take 10 ml of previously standardized 0.1 M EDTA solution into a clean & dried conical flask.
• Add about 4 gm ammonium acetate.
• Add 10 ml of acetic acid-ammonium acetate buffer. (7.71 gm of ammonium acetate in water + 5.7 ml acetic acid to produced 100 ml with purified water).
• Add 50 ml alcohol shake well.
• Add 2 ml Dithizone TS. As an indicator.
• Titrate the above solution with 0.1 M zinc sulfate with constant stirring and until the solution gives clear, rose pink color.
• Note down the burette reading.
• Calculate the molarity of solution by the following formula:

                                                         Molarity of EDTA x 10
Molarity of 0.1 M Zinc sulphate = ----------------------------------
                                                          Burette Reading

Method II

• Take 20.0 ml solution into a 500 ml conical flask.
• Add 5 ml of 2 M acetic acid and dilute to 200 ml with water. 
• Add about 50 mg of xylenol orange and hexamethylenetetramine until the solution becomes violet-pink. 
• Add 2 g of hexamethylenetetramine in excess. 
• Titrate with 0.1 M disodium edetate until the violet-pink colour changes to yellow.
• 1 ml of 0.1 M disodium edetate is equivalent to 0.02875 g of ZnSO4.7H2O.

Also see: Determination of Shelf Life of Solutions in Laboratory