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dissolving O2 into H20?

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aft:
 I thought oxygen was pretty insoluble in water...

though Im stumped as to why & how O2 (oxygen gas) can dissolve into H2O (liquid water)??

if anyone could shead some light on th issue, that'll be great.. =)

mike:
Oxygen dissolves better in cold water than hot water and in fresh water better than salt water.

Oxygen may enter a body of water through the air water interface, directly dissolving in the water or through the action of photosynthesis by aquatic plants.

Solubility of oxygen in cold water is 4.89cm3 per 100cc         [CRC]
Solubility of oxygen in hot water is 2.46cm3 per 100cc          [CRC]

lemonoman:
One way that O2 is dissolved in water is by diffusion from the surrounding air.  I'm not exactly sure why this happens...but it's probably because of atmospheric pressure.  Other ways it can be dissolved is through aeration (like, when water falls from a waterfall, it pushes air underneath and bubbles come up.  But some of the oxygen stays dissolved) and also from underwater plants, which give off O2 by photosynthesis.

If you're wondering about the mechanism, there isn't one.  O2 doesn't dissolve like regular ionic solids do (into + and - ions)...the whole molecule sits in the solution, solvated by water molecules, as pictured below:



Most information from this post is available from Texas A&M University, at "Water's the Matter"

constant thinker:
That's a good picture lemonoman. That's what a teacher once told me. He said the O2 was attracted to the H atoms and it formed weak hydrogen bonds.

aft:
oh... i c...  thanks guys  =)

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