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D4RR3N
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Quote: Originally posted by Σldritch  | D4RR3N i imagine it as a balloon filled with metal aerosol in pure oxygen gas. What is outside the ballon should not matter as long as it keeps a
reasonable pressure on it such as one athmosphere. If it did matter then the outside would be a part of what makes the mixture implode and it would
not make any sense to call it an implosive substance anymore because its ability to implode is not derived from the substance itself. Similarly we
dont call ethanol explosive because it burns, the ethanol air mixture is explosive.
An alkali metal would not work because as an aerosol it would instantly ignite. Also their oxides are volatile and very energetically favored so it is
likely it creates a higher pressure when it burns in isolation (if you can find heat of fusion and vaporization for them it should be possible to
calulate it). Perhaps you could inject liquid metal into a chamber of gas with an atomizer but i wonder if this would be quick enough to cause a
shockwave.
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So you are talking about cold oxidation of metal?
Is it possible to rapidly oxidise a metal without producing heat?
If liquid hydrogen was suddenly dispersed in the atmosphere forming a fine vapour cloud it would suddenly cool the atmosphere causing a drop in
pressure. That hydrogen then ignited would form water again causing a sudden drop in pressure.
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Σldritch
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| Quote: Originally posted by D4RR3N |
So you are talking about cold oxidation of metal?
Is it possible to rapidly oxidise a metal without producing heat?
If liquid hydrogen was suddenly dispersed in the atmosphere forming a fine vapour cloud it would suddenly cool the atmosphere causing a drop in
pressure. That hydrogen then ignited would form water again causing a sudden drop in pressure. |
No no. First it does not have to be oxidation. The only thing that is needed is one or two volatile products forming one or more nonvolatile products.
Heat will increase volatility like when you boil water so it should be minimized for an implosion to occur. The problem is usually strong bonds means
both low volatility and high enthalphy of formation. Ideally it would only have low volatility but that is impossible.
Look at this equation which is just two of the previous ones combined and rearranged for two gases:
ΔP = P1 - P0 = N·R·V-1·(T1·nc - T0·(na + nb))
ΔP is the difference in initial pressure (P0) and final pressure (P1) . If ΔP is negative it will implode since a vacuum is
being pulled. N and V do not matter, they just depend on how much of the hypothetical implosive you put in a cavity of volume V . R is the ideal
constant and in this case an approximation. Inside the outer paranthesis we can see that to make ΔP as negative as possible we want to increase the
amount of gas initially (na and nb) and that we want to minimize the amount of gas after ignition (nc). And similarly
we can see that we want as high a starting temperature as possible and as low a final temperature as possible. I think it is cheating to change the
starting temperature because you can never store it like you would store an explosive. (and the ideal implosive would then be a expanding sphere of
high energy particles that when cooled down would collapse into basicly nothing, far less interesting).
In short i mean relatively cold oxidation of metals. The colder the better but colder oxidation means weaker bonds forming which means higher
volatility which means less energy absorbed for vaporization and fusion which means a higher final pressure. If the final pressure exceeds the initial
pressure it is not an implosion anymore but an explosion.
Im not sure how to clarify further, did that do it?
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D4RR3N
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I would like to know what you mean by metal aerosol?
Do you mean a nano metal powder pressurised in a container with an inert gas such as Argon?
Anyway how fast do you think this reaction will take place, will it be fast enough to compare with an explosive?
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Simoski
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When the water droplet formed... elemental Hydrogen behaves very much like low pyrotechnic explosive H3 in that it is oxygen negative...the fire pulls
in O2 to complete the reaction.
The H3 composition burning tears oxygen out of the atmosphere, you can hear it ... tearing
It's exactly what happens with the Hydrogen balloon, it pulls in oxygen. It's on steroids of course, supersonic, but trust me the gas balloon will
implode and create a drop of water.
8 )
Your children will love it!
Here an H3 burn test for your pyro pleasure
H3 burn rate test
[Edited on 17-2-2020 by Simoski]
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AJKOER
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Suggested Safe Implosion Demo for a School Class
I once filled a plastic distilled water bottle with CO2, then add some cold water (or aqueous alkali) and seal the vessel.
Upon shaking, the vessel rapidly implodes!
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On the imploding airship, may I suggest a chain reaction involving H2 and the metal skin of the airship that was initiated by irradiation (from the
sun) where higher altitudes are associated with increasing intensity of radiation (from loss of atmospheric shielding from cosmic radiation).
Normally, chain reactions involving hydrogen can be poisoned by the presence of some oxygen. But, perhaps the hydrogen content was unluckily too high!
Speculated mechanics:
H2 + hv -> .H + .H
Al + .H -> Al.H (surface absorbed hydrogen atom or the creation of a hydride)
After this point, the chemistry gets complex, to quote a source (https://pubs.acs.org/doi/pdf/10.1021/acs.chemrev.6b00204):
"Metal polyhydride complexes offer the possibility of either photoinduced H loss or H2 loss, in addition to photodissociation of other ligands. "
So, further speculating:
Al.H + hv -> *Al.H
*Al.H + H2 -> Al.H2 + .H
continuing the chain reaction, albeit, via a complex mechanism, which is, actually, in line with the 'unexplained' classification.
[Edited on 21-2-2020 by AJKOER]
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TheMrbunGee
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Forming of a black hole is kind of an implosion.
While large depleted star cannot produce enough energy, to push against the gravity of its mass, and it collapses into a black hole - it's volume
vent from [whatever big number here] to basically nothing.
Extra energy coming only from stuff getting pulled and torned apart, + everything is super hot at this point anyway. (does it?)
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