* 0.1N Iodine solution ( 40 gm KI in 1 Ltr of Distilled water ).
* 0.05N Sodium Thiosulphate solution (12.5 gm Na2S2O3.5H2O in 1 Ltr Distilled water)
* 1% Starch solution
* Activated carbon
I Standardisation of Iodine solution
* Take 10c.c of 0.1N Iodine solution in conical flask.
* Add 2 drops of Starch solution.
* The pale yellow colour of Iodine Soln turns Blue.
* Titrate with 0.05 N Sodium Thiosulphate till it becomes Colourless.
* Burette reading corresponds to blank reading.(B)
* Weigh very accurately 0.2 gm of Activated carbon
* Introduce it into the Iodine flask which should be completely dry
* Add 40cc of 0.1N Iodine solution
* Shake the flask for 4 minutes and filter it
* Collect the filterate in a dry flask and Titrate 10cc of the filtrate against
Standard Sodium thiosulphate solution using starch as indicator
* Burette reading corresponds to (A)
Iodine value: C x Conversion factor; mg/gm
Factor:Mol wt. of iodine (127) x normality of iodine x 40 / Wt. of carbon x Blank reading
Note: Iodine test should be performed on dry basis
Carbon should be dried in oven at 110oC for three hours before weighing
Iodine value is expressed in mg/gm of carbon