Preparation and standardization of 0.05 M Zinc Chloride Volumetric Solution

1.0          Scope:

1.1                   The Procedure is applicable to Preparation and standardization of 0.05 M Zinc Chloride

Volumetric Solution.

2.0          Apparatus:

2.1        50 ml Burette (0.1 mL graduated).

2.2        500 ml Conical Flasks.

2.3        500 ml, 1000 mL volumetric flask.

2.4        100 ml measuring Cylinder.

2.5        50 ml Beaker.

2.6        Analytical Balance.

       (Use Class ‘A’ glassware)

3.0          Reagents:

3.1        Zinc Chloride (Analytical grade).

3.2        Dilute Hydrochloric Acid.

3.3        Dilute Acetic acid.

3.4        Xylenol Orange.

3.5        Hexamethylenetetramine..

3.6        Known molarity of 0.1 M Disodium Edetate volumetric solution.

4.0                Procedure:

4.1                   Preparation of Dilute Acetic acid solution:

4.1.1               Take 12 mL of Acetic acid in sufficient water to produce 100 mL.

4.2                   Preparation of Dilute Hydrochloric acid solution:

4.2.1               Take 12 mL of Hydrochloric Acid in sufficient water to produce 100 mL.

4.3               Preparation of 0.05 M Zinc Chloride:

4.3.1            Weigh accurately about 6.82 g of zinc chloride and transfer into 1000 mL volumetric

                    flask, add minimum amount of dilute Hydrochloric acid to dissolve and add water to

                    make upto the volume with water.

4.4              Standardization:                                           Molarity Limit :  + 10% (0.0450 to 0.0550)

4.4.1           Take 20.0 mL of 0.05M Zinc Chloride solution into a 500 ml conical flask, add 5 mL of

                    dilute Acetic 175 mL of water. To this add 50 mg of Xylenol orange mixture and                    

                    sufficient hexamethylenetetramine until the solution become violet-pink. Add about 2.0 g  

                    of hexamethylenetetramine. Titrate with known molarity of 0.1 M disodium edetate, with

                    constant stirring, until violet pink colour changes to yellow. 1ml of 0.1M disodium edetate              is equivalent to 0.00654 g of Zn.

   Calculation:

    Molarity of 0.05 M Zinc Chloride:

             Titer vol. of 0.1 M EDTA x Molarity of 0.1 M EDTA x 0.00654 x 1000                

       = -----------------------------------------------------------------------------------------------

                                       Wt. of Zinc Chloride (in gram) x 20

   Perform the standardization in triplicate

   % of RSD Limit : Not more than 0.2%

5.0               Storage:

5.1            Store Below at 25°C.

6.0               Shelf Life:

6.1             Shelf life of the above solution shall be one month from the date of preparation.

6.2             Restandardize the above solution once in 15 days.

                  Note: Discard the volumetric solution whenever sedimentation, crystallization or fiber

                  particles observed in the reagent bottle.