Absorption Equilibria and Henrys Law

The equilibrium of a species A between the gas and aqueous phase can be represented by 

FIGURE 7.2 Frequency distribution for liquid water content average values for various cloud types over Europe and Asia. 

The equilibrium between gaseous and dissolved A is usually expressed by the so-called Henry s law coefficient HA 

We should emphasize at this point that Henry s law is strictly applicable only to dilute solutions. If the solution is not sufficiently dilute, the concentration of the solute, [A(aq)], in equilibrium with pA deviates from Henry s law. These deviations from ideal behavior will be examined in Chapter 10. When considering the behavior of atmospheric gases at typical concentrations in equilibrium with cloud or fog droplets or large natural bodies such as lakes, Henry s law is generally accepted as a good approximation. 

TABLE 7.2 Henry s Law Coefficients of Some Atmospheric Gases 

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