Or do you know of a good site where I can ask chemistry questions?

With a name like "mole", I wouldn't guess you'd need any help with that subject

Why not post the question and see if anybody here can help?

Avagadro's number and all that.. we'll see what we can do.

OK, my question is this:

Do you think it would be possible to construct a self replicating molecule made up only of carbons that would feed on CO2?

No. Presumably you could construct some kind of very complicated, mechanical carbon molecule which could replicate itself. But "feed" on CO2? Where would the energy come from?

Why would you want to, and what if you couldn't stop it? And anyway, would it just release the oxygen and a free carbon atom or become something else? It sound like photosynthesis to me...

Yeah, it's not too far from plant respiration. If you add sunlight to the mix, as an energy source, you get a pretty effective (and sometimes tasty) replicator that's made out of mostly carbon.

I'd think its theoretically possible actually.

Take a dwarf star sized sphere of carbon and throw some CO2 at it. Voila, an even bigger 'molecule' of carbon. Oh wait, maybe it would have to be so big that the Carbon would undergo fusion. Meddling covalent bonds and all that.

And hey, you have a problem with other elements? Photosynthesis requires several others. Or are you imagining a nanotube nanorobot to clean up the greenhouse gases? You wouldn't be the first...

Well, I've had this idea for a while as a way to terraform venus. If we could make such a chemical and drop it into the planet's atmosphere, we might have something to work with. I was thinking that if we made something similar to benzene with one carbon missing, then those missing links could be strong enough to pull another carbon away.