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Re: O2 and CO2 solubilities
> Date: Wed, 21 Mar 2001 10:50:06 EST
> From: K12Trout at aol_com
> Subject: Re:O2 and CO2 solubility
> i don't know what exactly is said in limnology but,
> unless i'm gravely mistaken, it makes no chemical sense
> for co2 to be very soluble in water or for O2 not to be
> soluble. oxygen is a very polar molecule and forms
> hydrogen bonds with water very easily.
O2 isn't polar. It's a symmetrical diatomic molecule.
> carbon dioxide,
> despite carying two polar oxygen groups, is actually a
> linear molecule and ends up have very little dipole
It has no dipole moment at all, _but_ it has _two_ dipoles
back to back, with the C slightly positive and the O's slightly negative.
These charges let CO2 form associations with the water molecules'
dipoles and probably some hydrogen bonding as well.
> it is therefore hydrophobic.
No it isn't.
> as for
> "diffusivity", the diffusion constant for oxygen in
> water is, if i remember correctly, on the order of
>, ie very very very fast. i have witnessed this
> myself from fluorescence quenching experiments. if, on
> the other hand, we are talking about diffusion through
> membranes, it is true that co2 will pass readily through
> a membrane for exactly the reason it is not readily
> soluble in water.
This depends on the membrane. Different membranes let different
> all of this discussion is, however,
> largely inaccesible and totally unnecessary in the face
> of the common wisdom on the mailing list.
The point is that CO2 _is_ a lot more soluble in water than O2.
Paul Sears Ottawa, Canada