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CEE 320
Quiz #2
Environmental Engineering
F 5 February 2010
PLEASE WRITE YOUR NAME ON THE BACK
Quiz #2 solution key
Potentially useful data
1000 L = 1 m
3
Formula weight of chloroform (CHCl
3
): 119 g mole
1
1
μ
g = 10
6
g
PV = nRT where R = 82.05 x 10
3
mol
1
L atm K
1
Density of water: 1 g mL
1
= 1 kg L
1
= 1,000 kg m
3
UNIT CONVERSION EXERCISE AND EXPOSURE PATHWAYS
Note: be sure to show your work!
Tossing down an answer will not give you full credit.
You
must show how you arrived at your answer.
(a)
In Appleton, Wisconsin, the median indoor airborne concentration of chloroform (CHCl
3
)
was found to be 0.35
μ
g m
3
. Convert this concentration to a mole fraction in parts per
billion (ppb) assuming that T = 293 K and P = 1 atm.
X
=
mole fraction in ppb
X
=
C
CHCl
3
C
air
⋅
10
9
C
CHCl
3
=
0.35
μ
g
m
3
( )
10
−
6
g
μ
g
( )
1 mol
119 g
( )
=
2.94
×
10
−
9
mol
m
3
C
air
=
1 atm
82.05
×
10
−
3
atm
⋅
L
mol
⋅
K
( )
293 K
( )
=
4.16
×
10
−
2
mol
L
( )
1000
L
m
3
( )
=
41.6
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 Spring '10
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