Warning: Brake fluid is toxic and pool chlorine is corrosive.
Wear gloves when handling them.
This reaction also produces flames.
Work outside and fire safety protocols must be in place.
Greetings fellow nerds.
There are lots and lots, and lots more videos of the reaction of brake fluid and pool chlorine.
Together these chemicals spontaneously catch fire.
Now I try and focus on lesser known reactions or things that few others have done.
But I'm going to get onboard this overcrowded bandwagon as well as I'm going to talk about the science behind the reaction which a lot of other videos gloss over.
Now to do the reaction is quite simple.
The first component we need is pool chlorine.
In particular we want a brand that's made of calcium hypochlorite.
I've tried other pool chlorine chemicals like sodium dichloroisocynaurate or trichloroisocyanurate and those just don't work for this.
It has to be calcium hypochlorite.
The second component is Dot 3 brake fluid.
This brake fluid is made of polyethylene glycol which is key for this process.
Other brake fluids contain other chemicals and mixtures thereof that won't work.
Now all we do is mix them.
You don't even need to be precise about the quantity.
Using somewhat more brake fluid than pool chlorine works well.
I'm mixing it to ensure contact but to be honest,
you probably don't even need to do that.
Now stand back and wait.
At first nothing happens.
There is almost no outward sign of anything going on.
This unfortunately leads to a false sense of security and people can be dangerously off guard around the reaction when it finally begins.
I've seen reports of people that burned their hands off because they held bottles full of the mixture.
Anyway, after about thirty seconds or so, the mixture flares up and catches fire.
Yeah there we go.
It actually burns out quite quickly. Let's try that again.
I'm just going to pour some brake fluid on this mound of pool chlorine to show how robust the reaction is.
Okay, so what's actually happening?
Why is there a delay between mixing the chemicals and when it actually starts up?
Interestingly enough there is a forensic sciences paper that explores the process.
It doesn't take much imagination to figure out why law enforcement would like to forensic science data on the subject.
Anyway, brake fluid consists of polyethylene glycol.
As the name implies, it's a polymerized chain of ethylene glycol molecules.
Now polyethylene glycol, also known as PEG by us chemists, is by itself somewhat non-reactive.
In fact highly purified PEG is used as a laxative.
But don't drink brake fluid though as it has other toxic impurities.
Anyway, because it's non-reactive when you mix it with pool chlorine nothing appears to happen.
But actually, the pool chlorine is causing free radical fragmentation of the PEG.
It's cutting up the PEG into smaller more reactive molecules.
Now the exact ratio and products are hard to pin down but they are believed to consist of various aldehydes and ethylene gas.
All these products are highly reactive and in turn react by themselves with the pool chlorine.
This raises the temperature and increases the rate of the reaction further going into thermal runaway.
It's slow at first so it seems nothing happens but it is working.
Once it tips over it it explodes in heat, cause the leftover PEG itself to ignite.
So overall it's not really the PEG and the pool chlorine that are catching fire.
They first react to form the fragmentation products.
And those are what actually react to produce the tremendous heat needed to set the mixture on fire.
So now that we know that.
Can we test the reaction on a smaller molecule than PEG and affect the outcome? We can actually.
Now the fragmentation products are not easy to come by for the amateur.
But as said before, polyethylene glycol is a chain of ethylene glycol.
That should sound familiar because ethylene glycol is antifreeze.
It's not quite as reactive as the final fragmentation products but considerably more reactive than polyethylene glycol.
So here we are with some more pool chlorine.
Now we just add some antifreeze.
That actually occurred a lot faster than PEG.
With less decomposition needed it reaches the end of the fragmentation and starts heating sooner.
Interestingly enough it did not catch fire.
This is probably because ethylene glycol has a lower boiling point and higher autoignition temperature than brake fluid.
So it boils off before it can ignite.
A cool experiment is to actually do them side by side.
This shows the differences in reactivity and their bulk properties.
The antifreeze is more reactive and starts first, but is less flammable and boils away.
The brake fluid is less reactive and will take longer but can hold its heat long enough to actually ignite and catch fire.
So there you have it.
The science of brake fluid and pool chlorine.
Thanks for watching.
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