Preparation and Standardization of 0.05M Iodine using Arsenic Trioxide
Preparation: Dissolve about 14 gm of iodine in a solution of 36 gm of potassium iodide in 100 ml of water, add three drops of hydrochloric acid and dilute with water to 1000 ml. Standardise the solution in the following manner.
Standardisation: Weigh accurately about 0.15 gm of arsenic trioxide, previously dried at 105° for 1 hour, and dissolve in 20 ml of 1 M 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 g of sodium carbonate, dilute with 50 ml of water and add 3 ml of starch solution. Titrate with the iodine solution until a permanent blue colour is produced.
1 ml of 0.05 M iodine is equivalent to 0.004946 gm of Arsenic Trioxide.
Store in amber-coloured, glass stoppered bottles.
Calculation: = (Wt of Arsenic Trioxide × 0.5) / (BR × 0.004946)
Generally burette reading for this titration is found about 30.3ml
Determine 3 set of this titration and calculate RSD and mean of Molarity