Re: OT dynamite question for BD

Posted by KEB1 on April 25, 2011 at 20:27:03 from (97.124.132.241):

In Reply to: OT dynamite question for BD posted by teddy52food on April 25, 2011 at 10:25:29:

I debated for a while whether or not to dignify such a silly question with an answer. I haven't figured out whether you're just trying to stir up the board or if you actually believe some of this nonsense.

I assume what you're asking is whether the process you describe violates conservation of energy and/or the laws of thermodynamics. The answer is no.

All combustion reactions are exothermic, which means they release energy, typically in the form of heat. A chemical explosion is nothing more than a very fast combustion reaction, which releases a lot of heat quickly. That heat causes the products of combustion to expand rapidly, creating the explosive shock wave.

The energy released in a chemical explosion comes from energy stored in the chemical bonds holding the atoms together in the molecular structure of the fuel and oxidizer. Where does that energy come from, you ask. Why it was stored when the molecules were originally created via an endothermic reaction, i.e., one that requires an external source of energy. An example of an endothermic reaction is photosynthesis in plants, where energy from the sun is collected and used to synthesize the materials the plant is made from. We recover the energy that originally came from the sun when we burn plant material in an exothermic combustion reaction.

Note that none of this has anything to do with fission or fusion reactions, or magnets, or anything except the way atoms bond together to form molecules, which is well understood.

Let me give you an example of how this works. Consider the combustion of hydrogen with oxygen, which makes water and heat. One oxygen molecule, containing two oxygen atoms, combines with two hydrogen molecules, each containing two hydrogen atoms, to make two molecules of water. There are several intermediate steps in the reaction, but end result is that the energy stored in the chemical bonds of the two water molecules is less than the energy originally stored in the bonds in one oxygen and two hydrogen molecules. The extra energy is released as heat, hence an exothermic reaction.

Note that in a fuel cell, in the presence of a catalyst, the energy is (mostly, anyway) released as electricity rather than heat.

This is an interesting reaction because we can readily reverse it using relatively low levels of energy via a process called electrolysis. In electrolysis, energy in the form of an electric current passing through water excites the atoms in the water molecules enough to break the water molecules apart into the constituent atoms. At this point, the hydrogen and oxygen atoms are energetic enough to re-combine into separate oxygen and hydrogen molecules, which have now stored the energy put into the electric current used to break apart the water molecules.

Nowhere in any of these process has any energy been created or destroyed; it has simply been stored and released in various forms, and therefore none of these processes violate any of the laws of thermodynamics. So in answer to your original question, no, using a match to light a fuse to ignite an explosive does not violate any of the laws of physics.

I can guarantee you that the first person who actually succeeds in building something that puts out more energy that it consumes (in whatever form, and not counting nuclear reactions that convert matter to energy) will have every physicist in the world beating down their down to try to be the first to publish the results.

Keith

By the way, magnets do store energy in the form of the magnetic field, but that energy has to come from some source that originally created the magnet. In the case of the earth's magnetic field, the energy source is the kinetic energy of the earth spinning on its axis, which in turn creates eddy currents in the core, which in turn create the earth's magnetic field.

If you want an idea of how much energy is stored in a magnet, look at how much electricity is required to initially charge a new magnet, or to re-charge a magneto magnet...not very much.

Replies:

• Re: OT dynamite question for BD teddy52food 07:56:46 04/26/11 (0)

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