CHAP. 7: PHASE EQUILIBRIA [CONTENTS] 210
Solution
It follows from the specification thatV 2 (g)= 1dm^3 andV 1 (`)= 1dm^3. Substituting into (7.51)
givesβ= 1. We obtain Bunsen’s absorption coefficient from (7.52)
α= 1×
273. 15
273 .15 + 17
= 0. 941.
7.7.6 Liquid-gas equilibrium in more complex systems
This subsection deals with the solubility of gaseous mixtures in liquid, gas solubility in a mixture
of liquids, and gas solubility in aqueous solutions of salts.
- Solubility of gaseous mixtures in liquid
Henry’s law (7.40) can be directly extended to a (k-1)-component gaseous mixture
fi=KH,1ixi, i= 2. 3 ,... k , (7.54)
whereKH,1iis Henry’s constant of componentiin a liquid component 1. If the solubility
of gases is not too high,KH,1imay be identified with Henry’s constant in a binary system
containing a liquid component 1 and a gaseous componenti.
- Gas solubility in a mixture of liquids
In this case equation (7.40) applies, with Henry’s constant being the function not only
of temperature and pressure, but also of the liquid solvent composition. - Gas solubility in aqueous solutions of salts
Just like in a mixture of liquids, also in this case Henry’s constant depends on solvent
composition, i.e. the concentration of the aqueous solution. The presence of a salt may
increase gas solubility as compared with its solubility in pure water (this phenomenon
is known as thesalting-in effect), or (more often) it may decrease its solubility (the
salting-out effect).