The Briggs-Rauscher Iodine Oscillator

This reaction is an extremely interesting reaction that is a rare phenomenon in chemistry - an oscillating reaction. Three clear solutions are combined, and the color gradually changes to amber. Suddenly, the whole thing goes dark blue! This remains for a bit, then fades back into amber and the whole cycle repeats.

The full reaction mixture is a stew of many different chemicals:
Solution A:
0.2M KIO3
0.77M H2SO4

Solution B:
0.15M malonic acid
0.02M MnSO4
Starch (very tiny amount, since it is only slightly soluble)

Solution C:
4.0M H2O2

The three are combined together in equal amounts. There are as many as 30 different reactions happening simultaneously during the reaction. The paper I mention that talks about this in great detail is titled "The Oscillatory Briggs-Rauscher Reaction. 3. A Skeleton Mechanism for Oscillations" by Noyes and Furrow. I found it online someplace, but can't seem to locate it again for free.

Anyways I hope my explanation was helpful! It took me a while to get a good grasp of it myself. As always, thanks for watching and if you have any questions please let me know.

Category:

Science & Technology

Tags:

• iodine
• oscillator
• briggs

[hayjude99]

Can the Sodium Thiosulfate be the pentahydrate, because that's all I can seem to find easily.  Or is that what you're using anyway?

[mrhomescientist]

@hayjude99 Yeah that's all I use. You're just mixing it back into water anyway, so anhydrous is unnecessary.

[Oskar3855]

Can the malonic acid be substituted with any other more easily available acid? Also does it have to be KIO3 or does KI suffice?

Anyway, really awesome video.

Thanks!

[mrhomescientist]

@Oskar3855 Hey sorry for the slow reply. I don't think any of those substitutions can be made. According to the paper I list in the description, you need malonic acid and at least the iodate ion. Feel free to experiment though, there's a couple different versions of this experiment!

[SENSIBLECHEMIST]

0.77M H2SO4?? are you saying it won't work with 0.8M H2SO4???????!

[Axiss360]

The first time I saw this, I thought you cut the video when it turned black/blue.

[prozacgod]

Could you imagine seeing this for the first time. OMG I want to see this happen, in like a 30 gallon tank ;)

[hayjude99]

@mrhomescientist Exactly what i figured, cool

[DoktorKlawonn]

The cloudy precipitate @ 8:20 is manganese hydroxide or carbonte depending on what you've used to neutralize the mixture.

[chemicalsymphony]

What happens if you don't stir the reaction with a stir bar?