Gas Solubilities

							                   Gas Solubilities
Henry’s Law:          [A]equilibrium = SA · pA
“the partial pressure of a gas above a liquid is proportional to the
concentration in liquid under thermodynamic equilibrium”

Bunsen coefficient (β)
“the volume of a gas at STP (0°C and 1atm) that dissolves in one
unit volume of solution at temperature T with a total pressure of
1 atm and a fugacity (chemical potential--tendency of a gas to
prefer one phase of another, escape or expand) 1 atm”

Solubility function (F)
The Bunsen
coefficient

fugacity


            corrects partial pressure for the non-ideal behavior of gas

Combining the Bunsen coeff. with solubility




                 Dropped, for near-ideal behavior
Concentration of a gas in seawater is
determined by its partial pressure in
moist air. The relationship between the
partial pressures of moist and dry air.

Saturation water vapor



Solubility function (FA)
Solubilities decrease with increased temperature
Differences between gases can be caused by molecular weight and
other factors such as molecular interaction between the gas and
water.
For single element gases, more soluble with increased molecular
weight.