[chemicalLindsay]

whos heard of super critical co2 that is liquid (co2 sublimes normally) due to temperature and pressure changes  such as the pressure  between 10 and 100 atmosphere.This super critical co2 can dissolve basically anything including organic ,inorganic substances and synthetic polymers and much more stuff.My question is how exactly does the super critical co2 dissolve subtances (eg like you know how nacl dissolves in water by dissociation).heres a photo that I found of the apparatus used to create it that I found

[jdurg]

Yeah, this is the process they use to decaffinate coffee.  I used to know off-hand why it was able to do what it does, but I cannot recall as it was something in my high-school chemistry book.

[Scratch-]

I remember something about a gas becoming sort of a cross between a liquid and a gas and that allows for certain things in coffee to be absorbed into the gas but I dont remember the details. Perhaps this will jog Jdurg's memory.

[chemicalLindsay]

ok well supercritical co2 is a pretty darn good solvent and much more better than its hydrocarbon counterparts that are not only debilitating for the environment but also not as good solvent.there is some good information on supercritical co2 http://www.chem.leeds.ac.uk/People/CMR/moreco2.html

they say on that the rapid diffusion rates were what made it such a good solvent but how does it dissolve a solute.

Oh and here is a graph of the pressure,