Naked Science Forum

Non Life Sciences => Chemistry => Topic started by: pdshadow on 05/03/2008 07:53:09

Title: Does platinum make a good bullet?
Post by: pdshadow on 05/03/2008 07:53:09

Me and My roommate were having a debate, and he believes that Platinum, as well as the platinum molecule (difference?) cannot melt once they are solidified, and that A round from a weapon, such as a .50 caliber rifle, cannot penetrate a block of platinum of equal size (in length) to the bullet. I, on the other hand, believe it will, from my experience firing the weapon. the round in question is made of a  depleted uranium shell, measuring around 1.5 inches. the weapon itself pushes the round at roughly 12,000 foot pounds (~16 kilojoules). Now, i am not saying that the round would penetrate all the way through, but at least halfway.

The second question is that my roommate believes that H and H2 are completely different, and since they are, H can be frozen, and in turn has a melting point, but H2 cannot be turned into a solid. I am telling him that essentially, they are very similar, and EVERY element has the ability to go through the three phases of solid, L, and gas, whereas he says that is correct, but molecules cannot go through these phases. if that is so, how could you freeze water?

Thank you so much for helping us resolve these issues...

Title: Re: Does platinum make a good bullet?
Post by: lightarrow on 05/03/2008 09:03:29

Quote from: pdshadow on 05/03/2008 07:53:09

Me and My roommate were having a debate, and he believes that Platinum, as well as the platinum molecule (difference?) cannot melt once they are solidified,

What does it mean? Platinum melts at 1770 °C.

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and that A round from a weapon, such as a .50 caliber rifle, cannot penetrate a block of platinum of equal size (in length) to the bullet.

Don't know with existing weapons, but surely it would do it with a fast enough bullet; there is no limit to the kinetic energy a bullet can have.

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The second question is that my roommate believes that H and H2 are completely different,

they are

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and since they are, H can be frozen, and in turn has a melting point, but H2 cannot be turned into a solid.

It's the opposite: apart from extremely difficult conditions which I don't know if they are theoretical possible (not at present, however), H atoms will bind together when they are closer than in the gas (and, however, to stabilize a gas of atomic hydrogen is a Very complicated task), so liquid or solid H cannot exist; liquid or solid H2 does exist, you only have to cool it enough (-259 °C):
http://en.wikipedia.org/wiki/Hydrogen

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I am telling him that essentially, they are very similar, and EVERY element has the ability to go through the three phases of solid, L, and gas,

Yes, but you have to add that this is possible with the proper conditions: you cannot solidify CO₂, e. g., just freezing it at atmospheric pressure, you have to increase the pressure.

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whereas he says that is correct, but molecules cannot go through these phases. if that is so, how could you freeze water?

"Matter phase" is a concept which refers to the collective behaviour of many particles (atoms or molecules) so it's meaningless to talk about a molecule's phase.