Tag Archives: explosion

Sh*t I wont touch – The Legendary Picric Acid

Picric acid sounds like something out of Harry Potter – and it’s original concoction is the stuff of legend. Picric acid was more explosive than TNT.

Boom! Credit to Wikimedia commons
Boom! Credit to Wikimedia commons

Johann Rudolf Glauber first proposed pycric acid in 1742. It was first made from animal horn, silk, indigo and a resin using a recipe that looked almost identical to the ingredients necessary to bring Voldemort his body again.

The military caught wind of this chemical and found that it was highly effective in artillery as it was shock proof. Previous explosives like nitroglycerine would sometimes detonate in the artillery barrel which wasn’t a happy ending for anyone. The British, French and Japanese started toying around with it and it formed the basis for the following boomers:

– Explosive D (US)

– Lyddite (GBR)

-Shimose powder (JAP)

– Ecrasite (AUSTRIA)

– Melinite (FRA)

Why was it so dangerous?

Over time water evaporates from the substance leaving crystalline salts behind. These acid crystals are highly volatile and explode readily under friction or a change in temperature. The crystals react with metals and alkaline materials very easily, such as contrete, to form an explosive picrate salt – this particular salt caused booms that were bigger than TNT.

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Picric Acid; Image credit to National Institute of Standards and Technology (NIST)

The sensitivity of picrate acids comes from the NO2 groups on the main body (similar to TNT) – under a reaction they combust releasing a significant amount of heat and energy. Here’s a video to see what can happen:

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Sh*t I Won’t Touch – Chlorine Azide

Today we’re looking at a bag of fun known as chlorine azide. Chlorine azide was highly reactive, toxic and unstable – it was only really useful for figuring out what would blow up first if you opened a jar of it.

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What happened to every chemist that tried to play with it …
[Image courtesy of http://hqwide.com/death-dark-gray-chemistry-background-chemicals-blackboard-wallpaper-46976/]

No, seriously, that’s why they’re used. Their essential character is to make stuff around them change. Never put something next to a jar of Chlorine azide that you’re not comfortable seeing re-arranged in a suddenly violent fashion. The real challenge with this compound is finding something it WONT react with violently.

An excerpt from the 1943 JACS article on chlorine azide:

Owing to the extreme instability of the compound accurate determinations of the boiling and melting points have not been made as yet. Numerous explosions, often without cause, have occurred during experiments.

Wikipedia describes it in a similarly fun way:

‘It usually detonates violently, whatever the temperature, without apparent provocation’

What’s interesting to note is its brother, Sodium Azide, saves lives every single year – particularly throuhg its use in older air bags in cars.

Why is it so dangerous?

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A lovely molecule of chlorine azide – it’s the green bond you want to worry about ….
[Image courtesy of ChemNet http://www.chemnet.com/cas/en/13973-88-1/CHLORINE-AZIDE.html]

Chlorine Azide – it’s that green single bond that is the reason why this little man will blow up without provocation

A strongly, electronegative, chlorine is bonded with a very, very fragile single bond to a triple bond in the nitrogen compound. End of days occurs when the chlorine wants to find a new partner. Because this single bond is very, very fragile, all it takes is a partial electropositive charge on a neighbouring atom or molecule to break the Cl-N bond. The chlorine lovingly elects to take the rest of the compound with it. It’s like a trip-wired explosive. Because of this charmingly violent feature, it has little use in the lab other than to investigate substances and find out how on Earth you can stop this from happening.