Environmental Engineering Reference
In-Depth Information
3.43
1
The following two observations have the same explanation. River water is
often muddy, whereas seawater is not. At the confluence of a river with
the sea, a large silt deposit is always observed. Based on the principles of
chargedinterfaces,provideaqualitativeexplanationfortheseobservations.
3.44
2
Determine the ionic strength and corresponding Debye lengths for the
following solutions: 0.005 M sodium sulfate, 0.001 M calcium sulfate, and
0.001 M ferrous ammonium sulfate.
3.45
2
Typical concentrations of ions in natural waters are given below. Calculate
the ionic strength and Debye lengths in these solutions:
Concentration (mmol/kg)
Na
+
K
+
Ca
2+
Mg
2+
Cl
−
SO
2
4
NO
3
F
−
Medium
Seawater
468
10
10.3
53
546
28
0.05
0.07
Rainwater 0.27 0.06
0.37
0.17
0.22
0.12
0.02
0.005
Fogwater
0.08
-
0.2
0.08
0.2
0.3
-
1
3.46
2
Trichloroethylene is used as a dry cleaning fluid and is an environmentally
significant air and water pollutant. Obtain the enthalpy of vaporization
from the following vapor pressure data:
Temperature (
◦
C)
Vapor Pressure (mm Hg)
20
56.8
25
72.6
30
91.5
3.47
2
Estimate the vapor pressure of (a) chlorobenzene (a liquid) and (b)
1,3,5-trichlorobenzene (a solid) at a temperature of 25
◦
C. The melting
point of trichlorobenzene is 63
◦
C. Compare with the reported values in
Appendix 1.
3.48
2
Alkylethoxylates (AE) are nonionic surfactants that find widespread use
in cleaning, industrial, and personal care products. As such their envi-
ronmental mobility is predicated upon a knowledge of their adsorption
to sediments. Consider
n
-alkylethers of poly(ethylene glycol) of general
formula CH
3
-(CH
2
)
n
−
1
-(OCH
2
CH
2
)
x
OH, that is,
A
n
E
x
.If
n
=
13 and
x
=
3, it has a molecular weight of 332. The following data were obtained
for adsorption of
A
13
E
3
to a sediment (EPA 12):
Mass in Aqueous Solution (nM)
Mass Adsorbed (
μ
mol/kg)
175
25
270
45
350
80
450
100
DeterminewhethertheLangmuirorFreundlichisothermbestfitstheabove
data.
3.49
3
DDTisapollutantthatcanbetransportedthroughtheatmospheretoremote
locations. The sub-cooled liquid vapor pressure (below 110
◦
C) and liquid
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