| MadSci Network: Chemistry |
The reason that CO2 dissolves better in water than in CO is because of polarity. If you've ever heard that like dissolves like, this is based on the polarity of the molecules. CO is much more polar than H2O. If we look at the chemical structures of these two compounds, we can see why.
..
O C=O:
/ \ (Should be a triple Bond)
H H
Water Carbon Monoxide
:O=C=O:
Carbon Dioxide
Looking at these crude chemical structures, where the dots symbolize
unpaired electrons, we can see that CO2 is symmetrical and linear. All
charge forces act upon the "horizontal" axis and cancel each other out. For
the CO, we can see that lone electron pair off to the far right. This pair
of electrons sitting way out there makes this a vey polar molecule. Water
on the other hand is somewhere in between CO and CO2. Since water is less
polar than CO, and CO2 is still less polar than water, CO2 would tend to
dissolve more in H2O than CO. On the other hand, CO would dissolve in H2O
better than CO2 would. There is also a much simpler explination if you
assume that this is all done at atmospheric pressure and room temperature,
and that is that CO and CO2 are both gasses under these conditions and
gasses do not dissolve in each other, but diffuse into each other assuming
that they do not react.
Try the links in the MadSci Library for more information on Chemistry.