HOMEWORK#3
Due:3-3-14
[1] Table below illustrates chemical and physical properties of some organic compounds.
Heptane
Benzene
Toluene
p-Xylene
Chlorobenzene
Naphthalene
Anthracene
Fluoranthene
MW
(g/mol)
100
78.11
92.1
106.2
112.62
128.2
178.2
202.2
MP
(°C)
liquid
liquid
liquid
liquid
liquid
80
219
107
Sw
(mg/L)
0.01
1800
525
200
500
32
0.07
0.265
Density
(g/mL)
0.684
0.879
0.866
0.861
Log Kow
--2.3
2.69
3.15
2.84
3.3
4.45
4.9
Ks
(NaCl)
---0.2
0.2
0.2
[a] Estimate the γw for chlorobenzene, naphthalene, and anthracene using the
information in the provided table.
[b] Find the solubility of fluoranthene at 50% volume fraction methanol assuming
σc=log Kow.
[c] Compare your estimated value with measured value. Measured value at 50% volume
fraction methanol is 62 mg/L.
[2] Consider underground storage tanks buried near a shoreline where saltwater
intrusion occurs. Gasoline is leaking from the tanks. Assume gasoline is approximately
60% alkanes, which can be represented by heptane (average between butane, pentane,
octane etc.) and the rest is primarily benzene (5 wt% benzene, 22 wt% toluene, 13 wt%
p-xylene). Most gasoline has an average molecular weight of 105 g/mole and an
average density of 0.74 g/mL. Assume ionic composition and strength of
saltwater/groundwater mix in contact with the plume can be approximated with 0.25 M
NaCl. Estimate the aqueous phase concentration in mg/L benzene, toluene, and pxylene leaving the gasoline tank.
[3] Fedinger and co-workers developed a laboratory method referred to as the “wettedwall column method” for determining air-water Henry’s Law constants for pesticides.
This method consists of equilibrating the solute between a thin flowing film of water and
concurrent air stream in a vertical column. They reported a dimesionless Henry’s
constant for lindane (1,2,3,4,5,6- hexachlorocyclohexane) to be 8.1 x 10-5. If lindane
crystals are placed in a closed system and the second flask contains distilled water,
what will be the activity coefficient of lindane in the aqueous phase be after sufficient
amount of time has elapsed to ensure equilibration.
[4] Estimate KH (in atm L/mol) and KH’ (dimesionless) at 25 °C for [a] chlorobenzene and
[b] naphthalene using data provided above.
[5] Calculate the equilibrium distribution ratio, KH,SW of fluorine between air and
seawater at 25 °C.
[6] List the chemicals given in Table below in terms of increasing Henry’s constant (K H)
(e.g., A>B>C with A having the largest Henry’s Law constant.
Chemical
Naphthalene
p-Xylene
Hexane
Tetrachloroethane
MW (g/mol)
128
106
86
166
Tb (°C)
218
138.1
69
121.1
Tm (°C)
80.2
13.3
-95
-22.4
Sw (mol/L)
2.5x10-4
1.8x20-3
1.4x10-4
0.025
[7] List the chamicals listed in Table below in terms of increasing aqueous solubility (S w).
Chemcial
Benzene
Ethanol
Toluene
Phenanthrene
MW (g/mol)
78
46
92
178
Tb (°C)
liquid
liquid
liquid
100
Tm (°C)
80.1
78
111
340