Environmental Engineering Reference
In-Depth Information
The following data were reported by Hwang and Dasgupta (1985) for
the equilibrium between air and water for hydrogen peroxide at various
temperatures:
At 10
◦
C
At 20
◦
C
At 30
◦
C
P
i
C
i
P
i
C
i
P
i
C
i
(atm)
(mg/L)
(atm)
(mg/L)
(atm)
(mg/L)
2.8
×
10
−
7
1.1
×
10
−
6
8
×
10
−
7
0.08
0.05
0.104
3.5
×
10
−
7
2.2
×
10
−
6
1
×
10
−
8
1.3
×
10
−
3
0.10
0.10
4.4
×
10
−
7
2.8
×
10
−
6
5
×
10
−
9
6.5
×
10
−
4
0.12
0.12
1
×
10
−
9
1.6
×
10
−
4
(a) Obtain the
K
aw
for hydrogen peroxide as a function of temperature.
(b) Estimate the heat of volatilization of H
2
O
2
from water. Clearly state
any assumptions made.
4.3
2
(a) The heat evolved upon dissolution of atmospheric ozone into water
is determined to be
+
5 kcal/mol at 298 K. Given that ozone has a
Henry's constant of 9.4
×
10
−
3
mol/L/atm at 298 K, determine its
Henry'sconstantat273 K.NotethatthedefinitionofHenry'sconstant
is for the process air to water.
(b) If the atmospheric ozone concentration in a polluted air is 100 ppbv,
what is the concentration in equilibrium with a body of water in that
region at 298 K? Note that you need to assume no losses of ozone
other than absorption into water.
4.4
2
The following solubility data were obtained for an organic compound
(toluene)inthepresenceofhumicacidextractedfromawastewatersample.
Humic Acid Concentration
Solubility of
(mg of organic C/L)
Toluene (mg/L)
0
476
8
488
14
502
25
504
39
517
Estimate the
K
C
for toluene on the humic acid.
It was determined that the concentration of humic acid in the waste-
water pond was 20 g/m
3
. If the pure water Henry's constant for toluene is
0.0065 atm/m
3
/mol, estimate the partial pressure of toluene in the air in
equilibrium with the wastewater.
4.5
2
Consider 2L of a 2 mM solution of NH
4
OH in a closed vessel brought
to equilibrium with 100 mL of nitrogen. If the final pH of the aque-
ous solution is 8, what is the mass of ammonia in the gas phase at
equilibrium? The temperature is 298 K.
K
aw
=
0.016 atm/mol
/
L.
K
a1
=
1.7
×
10
−
5
M. Note that you have to derive the equation for the aqueous
mole fraction
α
NH
3
·
H
2
O.
Search WWH ::
Custom Search