Fusion for power?

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I did hear once from my inorgainc chemistry professor that he was working with heavy water and it behaved differently from light water in an experiment he was doing with mixing concrete. I'm not sure that would count as a chemical effect though.
heavy water is one of the few compounds where the isotope effect on it's chemistry is readily evident. the OD vs. OH bond dissociation energy is a few percent different. light water at STP has a pH of 7.0 vs. DOD has a pH of 7.4 under the same conditions.
 
The key distinction is that isotopes cannot be separated chemically, but must be separated by physical processes such as mass spectrometry, diffusion, or differences in light absorption properties. I believe ionization (and excitation) is considered a physical process not a chemical one, and perhaps the distinction is somewhat arbitrary and superficial.
Astronuc,

On the wiki page for MLIS, it is stated:

Instead of vaporized uranium of AVLIS, the working medium of the MLIS is uranium hexafluoride, which requires much lower temperature to vaporize. In every stage, the stream of UF6 is irradiated with an infrared laser operating at the wavelength of 16 µm. The mix is then irradiated with another laser, infrared or ultraviolet, are selectively absorbed by the excited 235UF6, causing its photolysis to UF5 and fluorine.
http://en.wikipedia.org/wiki/Molecular_laser_isotope_separation


if i understand this process correctly, then it would seem that the isotope is "selected" by preferentially exciting the vibrational modes of the species of interest. once the vibrational mode of that population is excited a UV beam is applied to excite the electronic state. it would then seem (and this is a big guess here) that there is a pathway between the two excited state surfaces. that is, there is ample vibronic coupling such that the electronic transition frequency for the vibrationally-excited species is different from the non-vibrationally excited species. if this were not true, then there would seem to be no reason for applying an IR beam. is this how the process actually works? clearly the born-oppenheimer approximation breaks down here.
 
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heavy water is one of the few compounds where the isotope effect on it's chemistry is readily evident. the OD vs. OH bond dissociation energy is a few percent different. light water at STP has a pH of 7.0 vs. DOD has a pH of 7.4 under the same conditions.
I believe that if you drank enough heavy water, it would posion you.
 
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Morbius

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yeah but not exactly...for example, when we solve for the 1s wavefunction of hydrogen it is the reduced mass that factors in and so a change in the mass of the nucleus will have a (albeit small) effect on the 1s orbital. while the difference is small, it can probably be detected spectroscopically (not entirely sure about that ...
quetzcalcoatl9,

not to nitpick - but the issues you raise about the wavefunction being different are true - but
those are usually classified as being differences in the physics NOT the chemistry.

We can separate isotopes by weighing them - as in the case of electromagnetic separation,
gaseous diffusion, ... but those differences are considered physical, not chemical.

We can separate isotopes by laser isotope separation; because as you point out the reduced mass
is used in calculating the wavefunctions; hence the ionization potentials are different - however,
again - those are called physical differences; NOT chemical.

When I or most scientists say "chemical" - we mean the chemical structure - how many valence
electrons, and what reactions are possible. In those cases, isotopes ARE chemically identical.

Dr. Gregory Greenman
Physicist
 

Morbius

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When I or most scientists say "chemical" - we mean the chemical structure - how many valence
electrons, and what reactions are possible. In those cases, isotopes ARE chemically identical.
Morbius,

I appreciate your response. I think the difference was then more of symantics than anything else.

Q
 
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Morbius

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Oops, I should think before I reach for the keyboard. I meant "drinking" and "poisoning" in the sense used in the Winipeadia for plutonium.
Paulanddiw,

Either way - heavy water behaves JUST LIKE ordinary light water in the human body for all intents and
purposes.

There's nothing particularly "poisonous" about heavy water because it is heavy water rather than
ordinary light water.

Heavy water, D2O; is the same as light water, H2O; with the exception that the Hydrogen atoms are
replaced by Deuterium atoms, which are the heavy isotope of Hydrogen.

Isotopes behave with the same chemistry. In terms of engaging in chemical reactions, the
Deuterium is just like ordinary Hydrogen - so there is no different "poisoning" problem with
heavy water.

Isotopes are different in their NUCLEAR properties - which is why heavy water behaves differently
than ordinary light water in a nuclear reactor. However, in the human body, light water and heavy
water are for all intents and purposed interchangeable.

In my previous post, I couldn't really say that heavy water isn't "poisonous"; because in sufficient
quantities, it is; just like light water is.

Dr. Gregory Greenman
Physicist
 

vanesch

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actually, if I understand correctly, there are small chemical differences between heavy water and light water, and indeed, if about 25-50% of your body water would be heavy water, several metabolical processes would be disturbed. As such, heavy water is "toxic" in a very very slight way, but if you would drink for more than a month of so *nothing else but* heavy water, you'd probably die or get seriously ill.
Drinking a glass (or a bottle) of heavy water is no problem. Drinking two bottles probably not, either. But drinking *only* heavy water for an extended period of time would be lethal.

http://rparticle.web-p.cisti.nrc.ca/rparticle/AbstractTemplateServlet?journal=cjpp&volume=77&year=&issue=&msno=y99-005&calyLang=eng
 
actually, if I understand correctly, there are small chemical differences between heavy water and light water, and indeed, if about 25-50% of your body water would be heavy water, several metabolical processes would be disturbed. As such, heavy water is "toxic" in a very very slight way, but if you would drink for more than a month of so *nothing else but* heavy water, you'd probably die or get seriously ill.
Drinking a glass (or a bottle) of heavy water is no problem. Drinking two bottles probably not, either. But drinking *only* heavy water for an extended period of time would be lethal.
this really isn't hard to imagine, since many (if not most) enzymes utilize water as an electron donor in their catalysis. given that the vibrational modes of D2O will be substantially different than that of H2O some enzymes may not function correctly. (infact, a friend of mine uses this isotope effect to study the reaction mechanism of enzymes - in particular the rxn rate kinetics).
 

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