PHYSICAL CHEMISTRY IN BRIEF

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).