Sulaiman
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What to do with Potassium Iodide ?
Due to JJay pointing to a relatively cheap source of Potassium Iodode
https://www.sciencemadness.org/whisper/viewthread.php?tid=90...
a few members, including me, will soon have 'spare' KI available for miscellaneous experiments,
so I started this thread to share ideas for the use of Potassium Iodide
I may try #3, #6 and re-try #7, I may possibly try #5 and #4.
#1 and #2 do not interest me.
1) Extract elemental iodine from KI
2) 'Elephant's toothpaste' - catalytic decomposition of hydrogen peroxide
3) 'Iodine clock' - reaction rate variables
4) 'Briggs–Rauscher' oscillating reaction
5) 'Golden Rain' - lead iodide synthesis
6) Electrolysis of KI to produce iodine and potassium hydroxide solutions
7) Synthesis of photo-sensitive silver iodide
Any more ideas for interesting uses of Potassium Iodide ?
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clearly_not_atara
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It can be oxidized to potassium periodate, which precipitates from solution. KIO4 is one of the most insoluble potassium salts, which is sort of
interesting. It can be used to cleave glycols. It dissolves in acidic solutions when the equilibrium (H4IO6- + H+ >> H5IO6) leans right.
Acetaldehyde from propylene glycol and glyoxylic acid from tartaric acid should be possible.
[Edited on 04-20-1969 by clearly_not_atara]
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JJay
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It has a lot of uses. I'm interested in it for making alkyl iodides. They can be used to make organometallics and quaternary ammonium compounds. It
can also be used to make potassium iodate, an important analytical reagent that is easy to purify and non-hygroscopic (I have some already).
Bromides (like sodium bromide) are cheaper and can be used instead of iodides in a lot of situations, but I think most iodides are easier to work
with.
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Heptylene
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You could:
- Make alkyl halides from KI and phosphoric acid.
- Make copper(I) iodide.
- Make 5-iodovanillin from KI + I2 and vanillin. Chemplayer made a video on this. I don't know what to use the product for however.
- Test your ethers for peroxides with KI solution.
- Do a Finkelstein reation with the alkyl bromide or chloride of your choice. Sodium iodide is more soluble in acetone therefore better for this
application but potassium iodide should still work to some extent. Diiodomethane can be made by Finkelstein on dichloromethane.
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Elrik
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The primary use of potassium iodide in my home lab is preventing hypothyroidism.
In my country hypothyroidism is common if fish is not consumed, many other countries are the same and the situation is spreading as iodine is phased
out of dairy production thereby eliminating milk as an iodine source.
A year or two after going vegan I developed hypothyroidism due to iodine deficiency. Iodine supplementation is rarely used to cure iodine deficiency
in the developed world, the medical industry prefers instead to put people on thyroid hormones for life.
Being a chem nut and a radical, when my situation was defined I went to my lab, got a dropper bottle, and made a solution of 200 micrograms potassium
iodide per drop of distilled water [supplying 150 µg iodine per drop]. I used 4 drops a day until the hypothyroidism was gone and now use 1 drop a
day to stay balanced. I've now been doing that for 5 or 6 years and the thyroid problem never recurred.
Theoretical chemistry is fun, applied chemistry is helpful!
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Sulaiman
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Assay
As more than one of us has ordered some of the KI pointed to by JJay,
it may be interesting to each assay our samples and compare notes,
and others with KI from other sources may want to check their stock ?.
We may all get different results but each of our own results will be more accurate due to sharing of hints/tips/tricks.
It may make a nice little collaborative project ?
My inclination is to titrate my KI (in solution) against Sodium Thiosulphate solution
with some starch to enhance colour changes.
My thiosulphate stock is claimed 99% purity and a few years old,
so I could maybe get +/-2% error testing 99% KI.
. How may I get more precise and accurate results ?
. What is the 'best' molarity to work at ?
. Does the use of starch enhance accuracy ?
. I have Class B 50 ml burettes, others may have better, most will not,
so maybe we can devise a simple weight-only titration ?
(on reflection, I think that it would be quite simple to do accurate weight-only titrations)
.
.
Anyone interested to do a group collaboration / co-operation ?
[Edited on 14-9-2018 by Sulaiman]
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JJay
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Sodium thiosulfate solutions degrade quite quickly. You can titrate sodium thiosulfate solutions (best to do immediately before use) with excess
potassium iodide in acetic acid with a standard solution of potassium iodate, easily prepared. I'm not sure I'd suggest preparing potassium iodate
from the same stock of potassium iodide that you are testing, but if it's reasonably pure (aside from water contamination), that would probably work
out OK. But if the test fails, you can really only get credible results if you use another source of potassium iodate.
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Sulaiman
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Assay ... continued
Just like simple acid : base titrations, we need an absolute reference.
Sodium thiosulphate pentahydrate may need re-crystalisation and drying or better
to get a reference accurate to better than +/- 1%.
Or maybe a different titrant, or gravimetric electrolysis, or some other method would be more appropriate ?
*********************************************************
I am willing to post a c5g sample of "99.9% Potassium Iodide" worldwide,
- up to probably seven or eight members taking part in this exercise, (if any)
to 'standardise' our results.
I can't guarantee the absolute accuracy/purity of my sample,
but at least we would all have a similar reference.
(if reqd. I could weigh the sample e.g. c5g +/-20mg ... say 1/2 % absolute error.)
U2U me if interested
- after publishing the results of your assay, based on your sample and method 
[Edited on 14-9-2018 by Sulaiman]
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DrScrabs
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Mood: Still evaporating..
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Or make some Iodo-starch paper as an indicator for nitrous acid, quite useful for the synthesis of diazo compounds or any other synthesis wich
involves nitrous acid. Then you can do the crazy scientist thing in every restaurant.
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fusso
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Quote: Originally posted by DrScrabs  | | Or make some Iodo-starch paper as an indicator for nitrous acid, quite useful for the synthesis of diazo compounds or any other synthesis wich
involves nitrous acid. Then you can do the crazy scientist thing in every restaurant. |
Wow never heard of
that. Where did you read this from?
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zed
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Thank you Elrik.
Hypothyroidism due to Iodine deficiency is uncommon in the U.S.. At least, as far as I am aware.
Here on the West Coast, we are surrounded by active Volcanoes, which occasionally erupt, and spew Iodine rich ash over much of the continent. Maybe.
https://www.sciencedirect.com/science/article/pii/S000928191...
Additionally, Common tablesalt (NaCl), which we generally use too much of, is often Iodized as a prophylactic measure.
A common reason to stockpile KI here, would be as an antidote to block the absorption of toxic radio-active Iodine, released via nuclear accident or
warfare.
https://emergency.cdc.gov/radiation/ki.asp
[Edited on 14-9-2018 by zed]
[Edited on 14-9-2018 by zed]
[Edited on 14-9-2018 by zed]
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zed
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Well, seems that a century ago, Iodine deficiency was a common problem in the U.S.A..
Me, I've always lived on the West Coast, we eat a fair amount of seafood, and we generally use Iodized salt (if we use salt). So, iodine deficiency
seems like a far-off problem. But, it really isn't. It is something worth thinking about.
http://journals.aace.com/doi/pdf/10.4158/EP14472.CO?code=aac...
Which means, I was wrong. The U.S. is on the edge of trouble, regarding Iodine deficiency.
Still not common here, but the problem could re-emerge.
And, Volcanic soils being rich in Iodine? Probably not true.
[Edited on 19-9-2018 by zed]
[Edited on 19-9-2018 by zed]
[Edited on 19-9-2018 by zed]
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clearly_not_atara
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According to the iodine levels in rainwater from that study, you'd have to drink tens of liters of rain per day to meet iodine requirements. Not high
enough for nutrition, but much higher than "ordinary" waters where iodine is present below 1 ppb.
[Edited on 04-20-1969 by clearly_not_atara]
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