When stuff blows up...?

Question

Ok, I don't do Chem at school so please don't just hand me a bunch of elements and numbers and say "this reacts with this and therefore this happens".

But when stuff blows up/explodes. Take fireworks, for example. I think they use potassium? And it reacts with something? What actually happens? I know that there is a reaction, but in that reaction, what happens?

Like, ok. You chuck a Mentos into a Coke can.

Boom.

I get that there is something that makes it explode... but is there something that agitates another thing and then pressure is built up or something? (Please don't laugh if that's wrong)

Answer 1

This is actually more of a physics question.



"An explosion is a sudden increase in volume and release of energy in an extreme manner, usually with the generation of high temperatures and the release of gases."



Basically, when something explodes, it has built up enough energy and pressure then released it so rapidly that the sudden release causes a pressure wave to be formed. A pressure wave is basically the front between two areas of differing pressure. In an explosion, the differential in pressure is high enough, compressed enough, and expanding fast enough that it has some physical effect (such as a an audible boom, or destruction).



Explosions, can range from something like a balloon bursting (though this is really only the audible kind) to something like an atom bomb exploding.



There are basically two types of explosives, one that explode when confined, and ones that don't require confinement.

The one that need to be confined are things like the mentos+diet coke, black powder, gun-cotton (nitrocelluslose), etc. These types need some sort of container so that they may be confined and build up pressure. The explosion comes when the container can no longer hold the pressure, and typically catostrophically destructs, releasing the pressure and resulting in an explosion.

Unconfined explosives are things like RDX (C4), TNT (trinitrotoluene), nitroglycerin, etc. When these substances explode, they are undergoing a chemical reaction so fast, that the energy and pressure generated creates an explosion.



Hope this answers your question.

Answer 2

With mentos the main effect is not a chemical reaction but a physical one. The mentos have lots of tiny pits on them that provide surface area for the Carbon Dioxide disolved in the soda to pool up and expand and leave the soda in a huge rush. Ive also heard chemical reactions take place but that its not that important. Rock salt works just as well if not better than mentos by the way.

Answer 3

An explosion is a sudded release of lots of gas. If this reaction is contained, like in the cardboard tube of a fire-cracker for instance, there is a huge build up of pressure. When this is released, (the container fails) the gas rushes out with a big boom.



A mentos in a coke can doesnt really classify as an explosion. Yes, if froths and bubbles, and if you contain it it goess boom, but the reaction itself is actually rather slow. What happens is that something in the mentos caused the carbon dioxide (CO2) in the coke to be realeased. So its similar to just shaking the bottle up.



One key feature of an explosive substance, is that they supply their own oxygen for the reaction.

When stuff burns, it combines with oxygen in the air. For instacne burning carbon, C, results in carbon dioxide, CO2.

But these reactions are SLOW.

If, however, we concider BLACK POWDER...(*giggle*) its a different story.



Black powder is a mizture of carbon, Sulphur, and potassium nitrate. The carbon and sulphur are the fuels, and they can burn in normal atmosphere. What makes this stuff a little more cool is the potassium nitrate. The formular is K(NO3), and the key feature we want for the explosion, is the big fat "O3" bit. For every one molecule of potassium nitrate, there are 3 oxygen atoms, just waiting to mix with the fuels. AS you know, you blow ona fire, it gets bigger. More air, more fire. same story here. AS the carbon and sulphur begin to burn in the air, the heat causes the potassium nitrate to split into its different substances. The oxygen now starts to bond to the fuels, and the reaction speeds up.



The products of the reaction are sulphur oxides and carbon oxides, all of which are GASES.... :) pressure builds, BOOM.



While writting the process out can take a while, the whole rection takes no time at all. Once that K(NO3) starts to release oxygen, all hell breaks loose.



Another important point, is that because the explosive CONTAINS oxygen, you can pack it into air tight containers, where it will still burn, despite the lack of air.







So thats about it. All explosives will contain a FUEL, and an OXIDISER. some examples are:



ANFO - Ammonium Nitrate Fuel Oil.

Nitroglycerin

Trinitrotoluene (TNT)



please note:



Ammonium "Nitrate" Fuel Oil

"Nitro"glycerin

Tri"nitro"toluene



MMMMM......the nitrate ion, (NO3), it your happy explosive friend :) :) :) :) :)



(hope i helped, and didnt come across as....a PSYCHOPATH.......hehehe)

Answer 4

Different processes can produce similar effects.



The mentos provide a place for the dissolved CO2 to latch onto and come out of solution.... really quickly.



Potassium has its electrons stripped off.



Sometimes thingsburn really quickly- like trinitrocellulose (flash paper).

Answer 5

i laughed