Iodine Clock Reaction

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remlap12
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Joined: 26 Jun 2014, 12:23
State/Location: NSW

Iodine Clock Reaction

Post 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!
Regards
remlap12
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linotas
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Joined: 21 Mar 2011, 22:39
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Re: Iodine Clock Reaction

Post 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
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remlap12
Posts: 340
Joined: 26 Jun 2014, 12:23
State/Location: NSW

Re: Iodine Clock Reaction

Post 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
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remlap12
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linotas
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State/Location: TAS

Re: Iodine Clock Reaction

Post 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?
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remlap12
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State/Location: NSW

Re: Iodine Clock Reaction

Post by remlap12 »

yep will do, thanks!
Regards
remlap12
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mtg
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Re: Iodine Clock Reaction

Post 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.
Marama T
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School: College
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Re: Iodine Clock Reaction

Post 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
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