[LAB] Preparation and Standardisation of 0.1N Iodine Solution – Lab Record

Aim:

To preapare and standardize 0.1 N Iodine Solution

Chemical requirements:

  • Iodine
  • Potassium Iodide
  • Dil HCL
  • Arsenic Trioxide (As2O3)
  • Methyl orange (Indicator)
  • Starch solution (Indicator)
  • Sodium hydroxide

Apparatus

  1. Burette
  2. Pipette
  3. Conical flask
  4. Beaker
  5. Glassrod
  6. Mortar& pestle
  7. Measuring cylinder

Procedure

  1. Dissolve 36 grams of potassium iodide in 100ml of water.
  2. Dissolve 14 grams of Iodine in the above solution
  3. Add 3 drops of dilute HCl
  4. Finally make upto 1000 ml with water

Standardisation of 0.1 N Iodine solution

  1. Weigh about 0.15 gn of arsenic trioxide which was previously dried at 1050C for 1 hour
  2. Dissolve in 20ml of 1 N sodium hydroxide solution by warming if necessary
  3. Dilute with 40 ml of water and 2 drops of methyl orange solution was added
  4. Dil.HCl was added drop by drop until the yellow colour is changed to pink; then add 2grams of sodium carbonate, dilute with 50 ml of water and add 3 ml of starch solution

Titrate with 0.1 N Iodine solution taken in burette until a permanent blue colour of starch is produced

Each ml of 0.1 N Iodine solution ≡ 0.00496 grams of Arsenic Trioxide

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