Preparation and Standardization of 0.1 M Ceric Ammonium Sulphate

Ceric Ammonium Sulphate Solution Preparation

• Dissolve 65 g of ceric ammonium sulfate with the aid of gentle heat, in a mixture of 30 ml of sulphuric acid and 500 ml of water.
• Cool, filter the solution, if turbid, and dilute to 1000 ml with water.
• Standardize the solution in the following manner.

Ceric Ammonium Sulphate Solution Standardization

• 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 sulfate 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 sulfate is equivalent to 0.004946 g of As2O3.
• Calculate the molarity of the solution by the following formula:

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