Preparation and Standardization of 0.1 M Ceric Ammonium Nitrate

Preparation of Ceric Ammonium Nitrate

• Shake a solution containing 56 ml of sulphuric acid and 54.82 g of ceric ammonium nitrate for 2 minutes.
• Carefully add five successive quantities, each of 100 ml, of water, shaking after each addition.
• Dilute the clear solution to 1000 ml with water.

Standardization of Ceric Ammonium Nitrate

• Weigh accurately about 0.2 g of arsenic trioxide, previously dried at 105° for 1 hour, and transferred to a 500 ml conical flask.
• Wash down the inner walls of the flask with 25 ml of a 8.0 % w/v solution of sodium hydroxide, swirl to dissolve, add 100 ml of water and mix.
• Add 30 ml of dilute sulphuric acid, 0.15 ml of osmic acid solution, 0.1 ml of ferroin sulfate solution.
• Titrate with the ceric ammonium nitrate solution until the pink color is changed to a very pale blue, adding the titrant slowly towards the end-point.
• 1 ml of 0.1 M ceric ammonium nitrate is equivalent to 0.004946 g of As2O3.
• Store protected from light.
• Calculate the molarity of solution by the following formula:

                      As2O3 in mg
M = ----------------------------------------------------
         Ceric Ammonium Nitrate in ml x 4.946
Also see: Determination of Shelf Life of Solutions in Laboratory