Multicomponent Equilibrium Thermodynamics - Elements of Environmental Engineering: Thermodynamics and Kinetics - page 105

125 Pa m 3 /mol; log K ow = 5.1; log K sw = 2.9; log K bw = 3.1. The solids
density is 0.015 kg/L and the bioorganism density is 1 kg/L. Determine
which compartment will have the highest amount of DMS?
3.9 2 The problem of oxygen solubility in water is important in water quality
engineering. Reaeration of streams and lakes is important for maintaining
an acceptable oxygen level for aquatic organisms to thrive.
(a) The solubility of oxygen in water at 1 bar pressure and 298 K is given
as1.13 × 10 − 3 molal.Calculatethefreeenergyofsolutionofoxygen
in water.
(b) It is known that atmospheric air has about 78% by volume of nitrogen
and 21% by volume of oxygen. If the Henry's constants ( K H ) for
oxygen and nitrogen are 2.9 × 10 7 and 5.7 × 10 7 Torr, respectively,
at 293 K, calculate the mass of oxygen and nitrogen in 1 kg of pristine
water at atmospheric pressure.
(c) If Raoult's law is obeyed by the solvent (water), what will be the par-
tial pressure of water above the solution at 98 K. The vapor pressure
of pure water is 23.756Torr at 298 K.
3.10 2 The Henry's constants for oxygen at three different temperatures are given
below:

T (K) K H (Torr)

2.9 × 10 7

293

3.2 × 10 7

298

3.5 × 10 7

303

(a) Calculate the heat of solution of oxygen in water assuming no
dependence on temperature between 293 and 303 K.
(b) Estimate the standard molar entropy of solution at 298 K.
3.11 3 The Henry's constants for ethylbenzene at different temperatures are given
below:

K aw (atm m 3 /mol)

T (K)

283 0.00326

288 0.00451

293 0.00601

298 0.00788

303 0.01050

(a) Express Henry's constant in various forms ( K H , K aw , K aw , and K x )
at 298 K.
(b) Calculate the enthalpy of solution for ethylbenzene.