Need help with article

[star_wars]

Ok I'm currently exploring other forms of life, mainly silicone and ammonia based life

I found out they can replace carbon and water in our system but I'm a bit stuck on the fact if they can replace both.

So we would have SI instead of C and NH3 instead H2O.

I think that assimilation (12H2O(l) + 6CO2(g)+ light→ C6H12O6 (glucose)(s) + 6O2(g) + 6H2O(l))

would become something like: Si3H4(s) → 3Si(NH)2(s) + H2(g)

This would make it rather tricky to live since your breathing H2 and thats a bit too flammable

So I need someone to help me work this and some more problems out, if your interested please reply

[sepulchrave]

Any reason why you chose Si₃H₄ (trisilaallene)? As far as I know (and I don't know much, I admit), it isn't very stable.

What about Si(NH)₂? I don't think that exists as a stand alone material.

Si doesn't really make many stand-alone molecules in the same way C does. I would guess that an Si/NH₃ form of life would have metabolic functions occurring on the surface of a Si substrate.

This could be regular Si, or SiO₂, or Si₃N₄. Perhaps:

Si₃N₄ (s) + 12 H₂ (g) + light → 3 SiH₄ + 4 NH₃

?

As far as I can tell you would need 664 kJ of light for every mole of Si₃N₄ converted. Silane (SiH₄) is fairly unstable; but I guess it might be possible to control the reaction of silane elsewhere in the organism to be a useful source of energy.

Anyway, I would look at the standard enthalpy of formation for various silicon-based compounds. Look at NIST's webbook for example.

---------

Footnote: The flammability of H₂ is only crucial in an O₂ (or, heaven forbid, an F₂) environment. In an NH₃ or N₂ environment H₂ is much more stable.

Edited December 9, 2009 by sepulchrave

[star_wars]

Yes the formula is flawed, I think it should be

2NH3(l) + Si3H4(s) → 3Si(NH)2(s) + H8(g)

And my chem teacher propposed Si(NH)2 as it is stable.

What I'm looking for tho is how photosynthesis would look if you substitute C with Si and H2O with NH3

I'm not completely sure if this would be the correct reaction since glucose it a lot larger and I'm not sure if this could make form poly-chains to mimic poly-sacharoses. Do you maybe have any suggestions to what could work better?

And the Footnote also really helped me out.

[sepulchrave]

What I'm looking for tho is how photosynthesis would look if you substitute C with Si and H2O with NH3

I'm not completely sure if this would be the correct reaction since glucose it a lot larger and I'm not sure if this could make form poly-chains to mimic poly-sacharoses. Do you maybe have any suggestions to what could work better?

Remember the only benefit of glucose is that it is easy to break it back down. All we need from a photosynthesis process is a mechanism for making free molecules that are quasi-stable, but can easily be broken apart when the organism needs some energy.

If Si(NH)₂ can easily react with H₂ and/or NH₃ to make energy then your process might work. I don't know what the enthalpy of formation of Si(NH)₂ is though.

That is why I proposed silane (SiH₄). You can also get long chains in the form Si_nH_2n+2 which is kind of analogous to the hydrocarbons found in gasoline.

I don't know of any reason why `life as we don't know it' needs to run on some equivalent of sugar rather than an equivalent of gas.

If you really want the analog of glucose just replace all the C's in glucose with Si, all the O's with NH, and all the OH as NH₂. You'd get Si₆N₆H₁₈, I think. I have no idea if that is stable though.

[questionmark]

Remember the only benefit of glucose is that it is easy to break it back down. All we need from a photosynthesis process is a mechanism for making free molecules that are quasi-stable, but can easily be broken apart when the organism needs some energy.

If Si(NH)₂ can easily react with H₂ and/or NH₃ to make energy then your process might work. I don't know what the enthalpy of formation of Si(NH)₂ is though.

That is why I proposed silane (SiH₄). You can also get long chains in the form Si_nH_2n+2 which is kind of analogous to the hydrocarbons found in gasoline.

I don't know of any reason why `life as we don't know it' needs to run on some equivalent of sugar rather than an equivalent of gas.

If you really want the analog of glucose just replace all the C's in glucose with Si, all the O's with NH, and all the OH as NH₂. You'd get Si₆N₆H₁₈, I think. I have no idea if that is stable though.

I think we need more of a reversible effect, something that combined with N would develop heat and at the same time combined with heat would split in N + whatever.