UG's Mad Scientists

Vixus wrote on Jul 19th, 2008 at 1:27pm : Any physicists here? You know how cool we are.

Yes, yes we are.

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Any physicists here? You know how cool we are.

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What's Dizzy done with the ridiculous number of mods?

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ciwwaf rulz wrote on Jun 23rd, 2008 at 10:18pm : WOOT!!!!!!!!! I got my grades and I got a B in chemistry (high school)

Congrats!

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WOOT!!!!!!!!! I got my grades and I got a B in chemistry (high school)

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My exams finished two weeks ago and I get my results next Friday. I think I done well. Watch my blog for results!

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So, how's everyone doing with their exams? I've only had maths ones so far, first science one is Chemistry on wednesday. Much fun


(Doing A-levels btw)

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ZanasCross wrote on May 18th, 2008 at 5:14pm : Guitardude19 wrote on May 15th, 2008 at 1:56pm : I read that the sun is not hot enough to cause fusion of Hydrogen to Helium but I read that due to quantum tunnelling, the nuclie can fuse. You read correctly. Due to the heisenberg uncertainty, the nuclei can violate conservation of energy for a small period of time, but a large enough time frame to begin the fusing process. This "loophole" is why the matter from all stars continuously fuses and never expands... because by the time it is fused, it doesn't have enough energy to explode past the gravity field of the star making it just re-fuse all the time.

Awesome, thanks for verifying that for me.

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Guitardude19 wrote on May 15th, 2008 at 1:56pm : I read that the sun is not hot enough to cause fusion of Hydrogen to Helium but I read that due to quantum tunnelling, the nuclie can fuse.

You read correctly. Due to the heisenberg uncertainty, the nuclei can violate conservation of energy for a small period of time, but a large enough time frame to begin the fusing process. This "loophole" is why the matter from all stars continuously fuses and never expands... because by the time it is fused, it doesn't have enough energy to explode past the gravity field of the star making it just re-fuse all the time.

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i like this group.....the words are green

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Civil_War wrote on May 15th, 2008 at 1:12pm : Guitardude19 wrote on May 12th, 2008 at 12:47pm : You are correct, it would have to be negative otherwise it cant occur. I just assumed that Gibbs could only be applied to a chemical system and not a physical nuclear reaction since nuclear reactions are governed by quantum rules. I read that the sun is not hot enough to cause fusion of Hydrogen to Helium but i but you...? lol, is there a character limit to these comments?

Gay.... Character limit! I didnt realise there was one :

I read that the sun is not hot enough to cause fusion of Hydrogen to Helium but I read that due to quantum tunnelling, the nuclie can fuse.

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Guitardude19 wrote on May 12th, 2008 at 12:47pm : You are correct, it would have to be negative otherwise it cant occur. I just assumed that Gibbs could only be applied to a chemical system and not a physical nuclear reaction since nuclear reactions are governed by quantum rules. I read that the sun is not hot enough to cause fusion of Hydrogen to Helium but i

but you...?

lol, is there a character limit to these comments?

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Civil_War wrote on May 12th, 2008 at 12:42pm : Guitardude19 wrote on Apr 29th, 2008 at 9:20am : Ja das is true. Once you hit good old Fe, any fusion reaction is now endothermic and takes in energy! I wonder if the Gibbs free energy for that process is +ve or -ve.... I know its not strictly a chemical reaction as such but the change in energy means it must still be a measurable process... If my understanding of Gibb's Free Energy is correct (have only studied A level Chemistry at this present time) then it would have to be -ve otherwise we couldn't get elements heavier than Fe. Though i'm sure my chemistry knowledge wanes a bit compared to a university chemist student such as yourself.

You are correct, it would have to be negative otherwise it cant occur. I just assumed that Gibbs could only be applied to a chemical system and not a physical nuclear reaction since nuclear reactions are governed by quantum rules.

I read that the sun is not hot enough to cause fusion of Hydrogen to Helium but i

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Guitardude19 wrote on Apr 29th, 2008 at 9:20am : Ja das is true. Once you hit good old Fe, any fusion reaction is now endothermic and takes in energy! I wonder if the Gibbs free energy for that process is +ve or -ve.... I know its not strictly a chemical reaction as such but the change in energy means it must still be a measurable process...

If my understanding of Gibb's Free Energy is correct (have only studied A level Chemistry at this present time) then it would have to be -ve otherwise we couldn't get elements heavier than Fe.

Though i'm sure my chemistry knowledge wanes a bit compared to a university chemist student such as yourself.

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Civil_War wrote on Apr 28th, 2008 at 4:03pm : There are no energetically favourable fusion reactions which take place after Fe. So it would have to absorb energy instead of emitting... Nuclear implosion maybe? ^^

Right, but one could create some havoc till one gets to Fe....
Implosion? You wanna create a black hole or something

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Civil_War wrote on Apr 28th, 2008 at 4:03pm : There are no energetically favourable fusion reactions which take place after Fe. So it would have to absorb energy instead of emitting... Nuclear implosion maybe? ^^

Ja das is true. Once you hit good old Fe, any fusion reaction is now endothermic and takes in energy!

I wonder if the Gibbs free energy for that process is +ve or -ve.... I know its not strictly a chemical reaction as such but the change in energy means it must still be a measurable process...

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There are no energetically favourable fusion reactions which take place after Fe. So it would have to absorb energy instead of emitting... Nuclear implosion maybe? ^^

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_Tim_ wrote on Apr 26th, 2008 at 2:37am : I'm pretty sure its U-235. Fission reactions are needed in the H bomb to create enough energy for the H atoms to fuse. U-238 absorbs the neutrons in the fission pr

Yeah, it is U-235...

Maybe someone could make a sun-like fission bomb that will never end exploding, making an H-bomb, next a He-bomb (helium), then a C-bomb, Fe-bomb, and whatever the fusion reaction follows....

Imagine a everlasting explotion, or at least a long and powerful one...

Eh, on a second thought, forget about that

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gonzaw wrote on Apr 24th, 2008 at 8:28pm : geluidsterroris wrote on Apr 24th, 2008 at 12:57pm : I wanna make a H-bomb and take over the world. I already know how to build one. Is there Uranium-235 on eBay? I think it is Uranium-238, but Uranium-235 or Plutonium-icantremember25 is better My father wrote a story about a terrorist making an H-bomb I think with commonday things (like stealing from a farmacy, and combining substances in a bathtub, etc)... You have to steal or get uranium oxide from any university or chemical house or whatever (like 50 pounds, with 20% uranium-235) and liquify it with hydrofluor acid I think, and then separate the U-235 from the U-238. Afterwards, enrich the U-235 (to like 90%) using some complicated bucket thing, and then turn it back into a solid metal form.... Then assemble everything...

I'm pretty sure its U-235.
Fission reactions are needed in the H bomb to create enough energy for the H atoms to fuse. U-238 absorbs the neutrons in the fission pr

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geluidsterroris wrote on Apr 24th, 2008 at 12:57pm : I wanna make a H-bomb and take over the world. I already know how to build one. Is there Uranium-235 on eBay?

I think it is Uranium-238, but Uranium-235 or Plutonium-icantremember25 is better
My father wrote a story about a terrorist making an H-bomb I think with commonday things (like stealing from a farmacy, and combining substances in a bathtub, etc)...

You have to steal or get uranium oxide from any university or chemical house or whatever (like 50 pounds, with 20% uranium-235) and liquify it with hydrofluor acid I think, and then separate the U-235 from the U-238. Afterwards, enrich the U-235 (to like 90%) using some complicated bucket thing, and then turn it back into a solid metal form....
Then assemble everything...

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