Ask A Scientist Chemistry Archive

name         Harold K. S.
status       educator
age          40s

Question -   thanks:
my question is this . If you mix powdered chlorine (shock treatment
for pools) and brake fluid together in approximately 2 minutes you get a
large cloud of white smoke followed by it bursting into flame. Is the
white cloud of smoke chlorine gas and if not what is it? What are the
effects of it ?
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Mr. Smith,

I think there might be more to the story. I have no direct experience with 
what is described in the question.

However, brake fluid is not a simple hydrocarbon-based hydraulic fluid. 
Rather, it is an ester that can absorb water form exposure to the 
atmosphere. That is one of the reasons why it should be changed 
occasionally -- rather than continually topped-up.

When a water-contaminated brake fluid is pressed into action under severe 
conditions -- like that which might be encountered under the repeated 
braking cycles in certain racing situations, the dissolved water sometimes 
boils. Consequently, that would prove disastrous to system performance -- 
the braking system is hydraulic, not pneumatic. The compressibility of the 
vaporized water would make the braking system almost useless because a 
compressible gas cannot transfer force nearly as efficiently as an
incompressible liquid.

If the chlorine source dissolves in and then reacts with water in the 
fluid, it could initiate oxidation of the ester. Perhaps that is what 
triggers the reaction he describes. if it did, it would make for a heck of 
a fire because the ester is an energy-rich fuel.

I do not think the smoke is chlorine gas. Chlorine is a faint greenish 
gas. Very likely, the smoke is particulates from the reaction described.

Regards,
ProfHoff 614
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Swimming pool "shock" treatment chemicals are chlorinated isocyanurates 
are strong oxidizing agents  releasing a large amount of hypochlorous 
acid. I do not think that brake fluid is a critical component. Any organic 
liquid (fuel) might do a similar thing. The isocyanurate probably reacts 
and generates a lot of heat which first vaporizes some hot liquid in the 
form of a mist. Eventually the oxidation gets so hot the liquid ignites.

THIS IS A VERY DANGEROUS "EXPERIMENT". THE OXIDIZING AGENT IS NOT INTENDED 
FOR THIS USE. IN A SWIMMING POOL THE LARGE AMOUNT OF WATER DISSIPATES THE 
HEAT GENERATED, BUT A "BUCKET" OF ORGANIC LIQUID IS GOING TO GET HOT, AND 
IGNITE (IF YOU ARE LUCKY} AND POSSIBLY DETONATE (IF YOU ARE NOT QUITE SO 
LUCKY). USING "SHOCK" CHEMICALS IN THIS WAY IS ASKING FOR TROUBLE. I 
CANNOT STRESS THAT TOO STRONGLY. THIS IS AN ACCIDENT WAITING TO HAPPEN.

Vince Calder
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