# Potassium iodide catalyst substitute
**URL:** https://boards.straightdope.com/t/potassium-iodide-catalyst-substitute/535445
**Category:** Factual Questions
**Created:** [April 8, 2010, 6:32pm UTC](https://boards.straightdope.com/t/potassium-iodide-catalyst-substitute/535445 "2010-04-08T18:32:47Z")
**Posts on this page:** 8
**Page:** 1
### Author:  [@TroutMan](https://boards.straightdope.com/u/TroutMan)
#### Post date: [April 8, 2010, 6:32pm UTC](https://boards.straightdope.com/t/potassium-iodide-catalyst-substitute/535445/1 "2010-04-08T18:32:47Z")
I’m doing some fun chemistry demos for a kid birthday party. I’m planning on making [Elephant Toothpaste](http://chemistry.about.com/od/chemistrydemonstrations/a/elephanttooth.htm), in which 30% hydrogen peroxide rapidly decomposes and makes foam (with the help of some dish soap). The reaction is typically catalyzed by potassium iodide, but I’m out of luck finding any. The party is this weekend, so I can’t order online. I understand it is sometimes used in photo developing, but a local photography shop doesn’t have it. Also no luck finding a survivalist store that would have the tablets (sometimes used to treat radiation exposure).
Is there some other easily obtained material I could get that would catalyze the reaction (almost) as effectively? Some web sites have recommended active dry yeast as a “kid-friendly” alternative, but I’m a little doubtful.
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### Author:  [@Squink](https://boards.straightdope.com/u/Squink)
#### Post date: [April 8, 2010, 6:36pm UTC](https://boards.straightdope.com/t/potassium-iodide-catalyst-substitute/535445/2 "2010-04-08T18:36:55Z")
[Manganese dioxide](http://en.wikipedia.org/wiki/Manganese_dioxide)will catalyze the breakdown of hydrogen peroxide.
You can get [Manganese dioxide from alkaline batteries.](http://www.youtube.com/watch?v=_uUfdJ5DsjQ)
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### Author:  [@beowulff](https://boards.straightdope.com/u/beowulff)
#### Post date: [April 8, 2010, 6:38pm UTC](https://boards.straightdope.com/t/potassium-iodide-catalyst-substitute/535445/3 "2010-04-08T18:38:30Z")
Blood.
Even cooler demo.
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### Author:  [@TroutMan](https://boards.straightdope.com/u/TroutMan)
#### Post date: [April 8, 2010, 6:46pm UTC](https://boards.straightdope.com/t/potassium-iodide-catalyst-substitute/535445/4 "2010-04-08T18:46:17Z")
> [@beowulff](#):
>
> Blood.
>
> Even cooler demo.
Perfect! You’re volunteering, right? 😃
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### Author:  [@si\_blakely](https://boards.straightdope.com/u/si_blakely)
#### Post date: [April 9, 2010, 10:03am UTC](https://boards.straightdope.com/t/potassium-iodide-catalyst-substitute/535445/5 "2010-04-09T10:03:39Z")
> [@beowulff](#):
>
> Blood.
Even better, liver (hold the Fava beans).
There are [catalase](http://en.wikipedia.org/wiki/Catalase) based solutions for neutralising Hydrogen Peroxide based Contact Cleaning solutions - that may be worth a try.
Si
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### Author:  [@Cheshire\_Human](https://boards.straightdope.com/u/Cheshire_Human)
#### Post date: [April 9, 2010, 3:21pm UTC](https://boards.straightdope.com/t/potassium-iodide-catalyst-substitute/535445/6 "2010-04-09T15:21:47Z")
Assuming you are going to experiment _ **before** _ the party, rather than hoping it works right the first time, you could try “tincture of iodine”, available at a drugstore. I don’t know if it would work, but it might. Then too, common table salt is chemically similar to potassium iodide, and iodized salt actually contains potassium iodide, so you might try those first.
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### Author:  [@acetylene](https://boards.straightdope.com/u/acetylene)
#### Post date: [April 9, 2010, 3:58pm UTC](https://boards.straightdope.com/t/potassium-iodide-catalyst-substitute/535445/7 "2010-04-09T15:58:34Z")
Manganese dioxide is messy. I have used pennies to catalyze the decomposition of 30% H2O2 but not for that particular demo. It’s worth a shot though.
BTW, where the heck did you obtain 30% hydrogen peroxide? Are you a chemist?
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### Author:  [@TroutMan](https://boards.straightdope.com/u/TroutMan)
#### Post date: [April 9, 2010, 4:11pm UTC](https://boards.straightdope.com/t/potassium-iodide-catalyst-substitute/535445/8 "2010-04-09T16:11:29Z")
> [@acetylene](#):
>
> Manganese dioxide is messy. I have used pennies to catalyze the decomposition of 30% H2O2 but not for that particular demo. It’s worth a shot though.
>
> BTW, where the heck did you obtain 30% hydrogen peroxide? Are you a chemist?
Chemist in a previous life, but that doesn’t help me now (obviously, since I can’t figure out a catalyst substitute on my own). I found it as half of a wood bleach product (Daly’s, which appears to be available only on the West Coast). It’s actually only 25%, but close enough. I’m also told that health food stores sometimes sell it, although I didn’t find any through that route. People drink it (diluted) because they think the extra oxygen has magical properties.