What effect does air pressure have on oxygen solubility?

What happens to the oxygen solubility when the pressure is increased? For example, if you have water at 21 C and the pressure is increased to 1520 torr then what would happen to the solubility of Oxygen?
-John Harris, Andy Reid

Oxygen is rather insoluble and unreactive with water. It can be expected to follow Henry's law, which says that the solubility of a volatile component is proportional to the the partial pressure of that component in the gas over the solution. If you double the air pressure, you'll double the partial pressure of oxygen, and so the solubility is expected to double.

You won't be able to use Henry's law at extremely high pressures, since at some point, the concentration of oxygen will be so high that you no longer have an ideally dilute solution. But it should hold up around 1520 Torr, where at 21°C the oxygen solubility should be roughly 18 mg/L.

Look for a high-pressure empirical solubility equation in the engineering literature if you need more than a back-of-the-envelope estimate.

Author: Fred Senese senese@antoine.frostburg.edu

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