Oxygen Solubility in Water vs. Pressure

At what depth underwater does air (oxygen) not exist or cannot exist due to the pressure?
- Nathan (age 30s)
San Diego, CA

It sounds as if you may be thinking of bubbles of oxygen gas, not individual molecules of dissolved O₂. The solubility of the molecules isn't very strongly dependent on the water pressure. At least up to 4 atm, about 40 m depth, it doesn't seem to care: . I haven't found a source for the solubility at higher pressures.

I haven't been able to find the exact pressure at which O₂ bubbles will collapse to a liquid at at room temperature. From an on-line  pictorial phase diagram it looks to be at a pressure of about 100 atm, or a depth of about 1 km. That pressure is physically reasonable, since it corresponds to the pressure where the O₂ gas density starts to get high enough for the molecules to be in a lot of contact.

Mike W.

(published on 12/29/2014)