Apparatus:
Volumetric flask,
conical flask,
beaker,
burette,
pipette,
filter paper
Reagents:
* 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
Procedure:
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)
II
* 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)
Calculations:
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
C=B-A
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
View Comments (5)
Gud day.I saw another formula about the iodine value of activated carbon,that they are using a conversion factor in the computation of iodine.The conversion factor depends on the normality of the filtrate?Is it the same with your formula?thanks
I've 2 questions for you regarding the determination of the value of iodine in powdered activated carbon:
1-(Collect the filterate in a dry flask and Titrate 10cc of the filtrate against
Standard Sodium thiosulphate solution using starch as indicator)
This sentence, I do not understand please can you tell me more clearly?
2-How to prepare 1% Starch solution in the form of liquid because of the starch in the form of a solid?
Take 100 ml distilled water in beaker and boil. Add preferably soluble starch to boiling water. Stop heating and stir .cool the sole and use
Just one question, where does the 40 come from in the conversion factor and does it have units?
I tried same but I didn't get Perl yellow colour of potassium iodine solution and not even blue color after add 2 drops of 1%starch solution.
I can't understand what mistakes I had done . Please reply with exactly how to make potassium iodine solution with point need to care about like sunlight and storage.