Explosives in a Vacuum - The Science Behind It

[drcathyc]

[SOLVED] explosives in a vacuum

Someone recently told me that explosives wouldn't work in a hard vacuum, that oxygen is required. Is this true? I know fire requires oxygen, but wouldn't there be some chemical reactions that don't require oxygen that can cause an explosive release of energy?

I'm a science fiction writer and want to make sure I get my science right (to the best of my ability!)

 

[mrjeffy321]

In most explosives, the fuel and oxidizer and closely mixed together…it does not require outside Oxygen to burn.

Although Oxygen gas is a common oxidizing substance which is used in the combustion of many fuels (such as in the example of a camp fire), it is not the only oxidizer.

Take, for example, the reaction between sugar (sucrose) and Potassium Chlorate,
C12H22O11 + KClO3 --> CO2 + H2O + KCl
In this case (when properly balanced), no Oxygen from the atmosphere is required for the reaction to proceed, all of the ‘oxygen’ the reaction needs is present in the oxidizer…in this case, solid Potassium Chlorate.
If this reaction is preformed under the proper conditions (i.e. reactants thoroughly mixed, confined space, small particle size, …) it can lead to an explosion.

 

[lightarrow]

Someone recently told me that explosives wouldn't work in a hard vacuum, that oxygen is required. Is this true? I know fire requires oxygen, but wouldn't there be some chemical reactions that don't require oxygen that can cause an explosive release of energy?

I'm a science fiction writer and want to make sure I get my science right (to the best of my ability!)

In addition to what correctly said mrjeffy321, what you say is true only in the case in which there is an explosion with fuel in eccess with respect to oxidant, for example if a container of gasoline explodes: there will be a lot of gasoline not previously mixed with air, so most of the fuel will burn _after_ the initial explosion, making the total explosion more powerful when the fuel finds the oxygen during its expansion in the air.

However an "explosive" is a substance or mix of substances where fuel and oxidant are very intimately mixed together (or inside the same molecule), so it won't need air at all; that fact is one of the reasons it's explosive...

 

[DaveC426913]

If I understand it correctly, nitroglycerin is a self-contained chemical reaction. The solid molecule is very unstable. When jostled, it rearranges itself in another configuration of lower energy. The new configuration is that of several gases, all of which, partly because of the released heat and partly because they are gases, want to expand very rapidly.

 

[drcathyc]

Thanks for the help here. I was pretty certain the other person was wrong in what she said (in regard to a story I had written), but I wanted to make sure.