Multicomponent Equilibrium Thermodynamics - Elements of Environmental Engineering: Thermodynamics and Kinetics - page 108

water molecules will be in the droplet? Conventional wisdom says that the
number of water molecules on a drop should be less than the total number.
Calculate the ratio of water molecules on the surface to the number in the
droplet. Comment on your result. Molecular area of water = 33.5Å 2 .
3.23 1 The value of K ow as a ratio of molar concentrations is always smaller than
that expressed as ratio of mole fractions. Explain why?
3.24 3 Using the values from Appendix 3 and the rules given in Lyman et al.
(1990),obtainthelog K ow forthefollowingcompounds.Obtainthecorrect
structures for the compounds from standard organic chemistry texts:
(i) Pentachlorophenol,
(ii) Hexachlorobenzene,
(iii) p,p -DDT,
(iv) Lindane,
(v) Phenanthrene,
(vi) Isopropyl alcohol
3.25 2 The melting point of naphthalene is 353.6 K. Its solubility in water at room
temperature has been measured to be 32 mg/L.
(a) Calculate the activity coefficient of naphthalene in water.
(b) What is its ideal solubility in water?
3.26 2 The solubility of anthracene in water at different temperatures has been
reported by May et al. (1977) as follows:

t ( ◦ C)

Solubility ( μ g/kg)

5.2 12.7

10.0 17.5

14.1 22.2

18.3 29.1

22.4 37.2

24.6 43.4

Determine the excess thermodynamic functions for the solution of
anthracene in water at 25 ◦ C. Δ H m is 28.8 kJ/mol.
3.27 1 The cavity surface area for accommodating benzene in water is 240.7Å 2 ,
whereas the molecular area of benzene is only 110.5Å 2 . Can you explain
the difference?
3.28 2 Calculate the aqueous solubility of hexachlorobenzene in water using
appropriate correlations and calculations involving (a) molecular area, (b)
molecular volume, and (c) molar volume.
3.29 2 The compound 2,2 ,3,3 -tetrachlorobiphenyl is a component of Aroclor,
a major contaminant found in sedimentary porewater of New Bedford
harbor, MA. In order to perform F&T estimates on this compound, we
need, first and foremost, its aqueous solubility in seawater.
(a) Use the fragment constant approach to obtain K ow .
(b) Obtain the aqueous solubility in ordinary water from the appropriate
K ow correlation.
(c) Check the uncertainty in the prediction using alternate methods such
as molecular area (225.6Å 2 ) and molar volume (268 cm 3 /mol).