Sciencemadness Discussion Board

mythbusters/rocket fuel question

havokane - 7-6-2006 at 14:55

i was watching the exploding pants episode, and while they were making the exploding pants, they tried to cover up the recipe, but i saw the label of the herbicide. it was ammonium nitrate, but whats the acid they mix with it. picric? nitric? im just curious. it has a similar, albiet less stable reaction as potassium nitrate and sugar. would potassium nitrate and a specific liquid have a similar reaction? the nitrates act as the oxidizer, and the sugar acts as an fuel, but what acid has properties that act as a fuel?

12AX7 - 7-6-2006 at 15:25

Nah, it was sodium chlorate. AN isn't shock sensitive. Not like chlorates are, anyway.

I don't know of any acid that acts as a fuel, outside of carboxylic acids (acetic acid burns), which aren't as strong as mineral acids. About the most acidic fuel (as such) would be an -ide, such as silicide or sulfide, the acid of which would be hydrosilic (H4Si, or more often SiH4, silane) or hydrosulfuric acid (H2S, hydrogen sulfide), neither of which is particularly acidic, or even particularly stable in water (an acid itself, hydro-oxygenic acid if you will ;) ).


havokane - 7-6-2006 at 16:06

thanks for the help. the only reason i said acid as a fuel, is because i remember them saying something about adding an acid. thanks for correcting me about the oxidizer though, so now i can scour google somemore to look for the mix.

12AX7 - 7-6-2006 at 16:28

The thing about chlorate is, when you add acid, you release unstable chloric acid, which tends to explode when it comes in contact with organic material, like cotton pants.

Pants (or a mixture of the salt with sugar or starch or just about anything else burnable) impregnated with sodium or potassium chlorate will ignite when touched with a rod wetted with sulfuric acid. Popping will be heard when the rod is touched.


havokane - 7-6-2006 at 17:27

i guess you havent seen that particular episode, but what they did was mix up the herbicide with and unknown liquid, dipped the pants in it, let it dry, and then tested ways to ignite it. friction, flame, radiant heat, and impact. it detonated from every method except friction. so it wasnt the chemical reaction itself that set it off. but its nice to have a conversation with a person willing to share information for a change.

12AX7 - 7-6-2006 at 18:49

Oh, well then that's just water... sodium chlorate is rather soluble...


Odyssèus - 8-6-2006 at 09:33

They could have been converting the cotton to nitrocellulose. The acid would be to create nitric acid from AN then.

Swany - 8-6-2006 at 10:39

They tried that, and had an amazing runaway. I don't really understand what you are saying.

havokane - 8-6-2006 at 11:17

if your refering to me, im just trying to find out what the 2 chemicals were that they used. if you are talking to odysseus, i dont really understand his post either.

Odyssèus - 8-6-2006 at 11:19

For example:

NH4NO3 + H2SO4 => (NH4)2SO4 + HNO3
2HNO3+ C6H10O5 => C6H8(NO2)2O5 + 2H2O

Guess my first post didnt come out very clearly.

[Edited on 8-6-2006 by Odyssèus]

Pommie - 9-6-2006 at 05:58

If it's the episode I remember, it was the discovery of nitrocellulose. Pants being cotton with a bit of mixed acid added.


havokane - 9-6-2006 at 08:46

it wasnt about the discovery of nitrocellulose, it was something about farmers in NZ whose pants were randomly exploding. they attributed it to a new herbicide that was intorduced to stop some supergrass the killed crops and cattle.

DeAdFX - 9-6-2006 at 19:54

Originally posted by Pommie
If it's the episode I remember, it was the discovery of nitrocellulose. Pants being cotton with a bit of mixed acid added.


If I got Nitric/sulfuric acid on my clothing nitrocellulose would the least of my worries. I don't think having discolored slabs of meat would be the most enjoyable thing.

urbs - 22-8-2006 at 06:27

Episode 53, "Exploding Pants" will air again September 9, 2006 @ 6:00 p.m. check your local schedules. My guess, although I haven't seen the episode, is that the material in question is Sodium Chlorate, previously a common herbicide. Quite water soluble, it would end up impregnated in the cotton fibers of jeans. NaClO3 has a low temperature of decomposition, and gives up its oxygen easily causing the combustion of many organic materials. Shimizu's H3 is a KClO3 + charcoal burst charge that is said to be more stable than many other chlorate comps, but is not known to be tame by any estimation!!