The ultimate guide to Belousov- Zhabotinsky (BZ) Reaction- Part 2 (Petri dish version) #oscillation

Hinzugefügt: 2026-05-22

[00:00:01]In this video, I'll show you how to perform the iconic Belousov-Zhabotinsky reaction in a Petri dish.

[00:00:09]Remember that pulsing chemical heartbeat from my last video?

[00:00:13]What if I told you we can create those self-organizing traveling alien waves from the same stock solutions?

[00:00:21]The BZ reaction can be performed in both a beaker and a Petri dish. Most online tutorials will only show you completely different recipes for each of them. But today, I'll show how to perform the Petri dish version with the same stock solutions from last time. No redo the weighing of the starting materials. No extra math. Here's a list of all the ingredients you need. Pause here to take notes if needed.

[00:00:49]In a Petri dish, we add 5 ml sodium bromate, 2 ml 20% sulfuric acid, and 1 ml malonic acid. Then add 0.5 ml sodium bromide solution. Gently shake the mixture until it's uniform. Wait until the mixture turns from yellow to colorless. This is extremely important because if you add the ferroin indicator too early, this is what would happen.

[00:01:19]After the mixture becomes completely colorless, you can add several drops of ferroin. Gently shake the mixture until it appears uniform. Then leave it on a level surface undisturbed. It may take 1 minute or two to start the reaction.

[00:01:35]Soon, you should start to see the slow formation of the traveling waves. Keep in mind that the BZ reaction is a great example of a chaotic system, which means a small change in the starting condition in vastly different outcomes. So, no two runs will ever look the same. But in case that the reaction doesn't start in the Petri dish after a long time. It usually means the concentrations of the starting materials are not correct. You can add sodium bromate or malonic acid drop by drop until [music] this mixture is capable of producing traveling waves.

[00:02:12]Another common problem is that the traveling waves appears to be too thin and difficult to observe, just like this one. The solution to this problem is adding a co-catalyst, either manganese sulfate or diammonium cerium for sulfate would work. Let's add one drop of the cerium for solution into the mixture.

[00:02:32]You can see once the oscillation starts again, the traveling waves appear to be much thicker. Adding manganese sulfate as a co-catalyst can make the waves thicker as well. And there is one final surprise waiting for us. At the end of the reaction, you can even see the traveling waves of manganese dioxide.

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