How do you Make a 0.05 M Iodine Solution?

Preparation of 0.05 M Iodine Solution

Dissolve 14.0 gm of iodine in a solution of 36.0 gm of potassium iodide in 100 ml of water, add 3 drops of hydrochloric acid and dilute with water to 1000 ml. Standardize the solution in the following manner.

Standrazition of 0.05 M Iodine Solution

Weigh accurately 0.150 gm of arsenic trioxide previously dried at 105⁰C for 1 hour and cooled in desiccators, dissolve in 20 ml of 1M sodium hydroxide by warming (if necessary ) dilute with 40 ml of water, add 0.1 ml of methyl orange solution and add dropwise dilute hydrochloric acid until the yellow colour is changed to pink. 

Add 2 gm of sodium carbonate dilute with 50 ml of water and add 3 ml of starch solution. 

Titrate with 0.05M iodine solution until a permanent blue colour is produced.

Each 1 ml of 0.05M iodine is equivalent to 0.004946gm of As₂O₃.

Calculation

               Wt. of Arsenic trioxide (mg) x Potency of Arsenic trioxide × 0.05
  Molarity  =  ----------------------------------
                    Volume Consumed (ml) x 4.946 × 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%.