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Iodine Clock Reaction
Posted: 29 Nov 2017, 11:28
by remlap12
Hi all,
I am making Solution A for the Iodine Clock Reaction following this recipe:
0.6g Starch
4.1g Sodium Acetate
30mls Acetic Acid
50g Potassium Iodide
4.7g Sodium Thiosulfate
The solution is very cloudy.
My question is, has anyone made this particular one and if so how long should it take to go clear?
What am I doing wrong?
Thanks in advance!
Re: Iodine Clock Reaction
Posted: 29 Nov 2017, 11:39
by linotas
I did this last week. It worked perfectly. The recipe was slightly different to yours though:
Solution A:
4.1g Sodium Acetate
0.6g soluble starch
50g KI
9.4g sodium thiosulphate
1L water
Solution B:
30ml Glacial acetic acid
500ml 3% H2O2
470ml water
Re: Iodine Clock Reaction
Posted: 29 Nov 2017, 11:59
by remlap12
So linotas, was your solution A clear?
I'm trying another batch but it's not looking good!
My solution B is just 500mls 3% Hydrogen Peroxide and 500mls distilled water
Re: Iodine Clock Reaction
Posted: 29 Nov 2017, 12:56
by linotas
Yes, both solutions were clear. It sounds like the starch isn't dissolving if it is cloudy. Maybe try putting the acid in solution B and see if that works?
Re: Iodine Clock Reaction
Posted: 29 Nov 2017, 13:31
by remlap12
yep will do, thanks!
Re: Iodine Clock Reaction
Posted: 11 Oct 2023, 08:54
by mtg
Wondering if anyone has an update for this reaction.
my old recipe is
1. 0.10M Potassium Iodide (KI 16.60 g/L)
2. 0.01M Sodium Thiosulphate (Na2S2O3.5H2O, 2.48g/L)
3. 3% Starch
4. 0.04M Sodium Persulphate (Na2S2O8. 9.52g/L)
mix 100ml of 1., 10ml of 2., and 1ml of 3.,in a 500ml flask. Add 100ml of 4., and swirl the flask. A blue colour will appear in about 15 seconds. (From Colourful chemistry, John Gipps and Eric Friedman)
As I recall it didn't work that quickly either.
Re: Iodine Clock Reaction
Posted: 11 Oct 2023, 09:51
by Marama T
Here's one that uses H2O2. Using stronger H2O2 results in a faster reaction.
https://edu.rsc.org/experiments/iodine- ... 44.article