Exam 1A solution (1)
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School
Pennsylvania State University *
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Course
370
Subject
English
Date
Feb 20, 2024
Type
Pages
5
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CE 370 – Introduction to Environmental Engineering Exam 1 Page 1 of 5 CE 370 – Exam 1 (A) – 40 total possible points
Name ___________________________________________________________________ Section (Circle one): Section 1 (12:05 – 1:20 PM) Section 2 (1:35 – 2:50 PM) Scientific Prefixes Multiplier Prefix Symbol 10
15
peta P 10
12
tera T 10
9
giga G 10
6
mega M 10
3
kilo k 10
-3
milli m 10
-6
micro µ 10
-9 nano n 10
-12
pico p
CE 370 – Introduction to Environmental Engineering Exam 1 Page 2 of 5 Multiple Choice / Quick Calculations Questions (3 points each). Problem 1.
You are comparing the acute risks of two chemicals. Chemical A has a much smaller LD
50
value than Chemical B. Which chemical has a higher toxicity? a.
Chemical A b.
Chemical B c.
There is not enough information given to answer the question. Problem 2.
Due to an accidental spill, a local pond became contaminated with radium, which is radioactive. Assume that no water flows into or out of the pond over time and that it is well mixed. Which model system best describes the pond? a.
A CSTR b.
A plug flow c.
A batch reactor Problem 3.
Which of the following expressions is an example of zero-order kinetics? a.
!"
!#
= ࠵?
b.
!"
!#
= ࠵?࠵?
c.
!"
!#
= ࠵?࠵?
$
Problem 4.
The concentration of carbon tetrachloride (CCl
4
) in a water sample is 1 ppm. Calculate the concentration in mol/L: ______6.5E-6_______ mol/L Problem 5.
The concentration of a contaminant in a river is 5,000 ppb. Calculate the concentration in ppm: ______5_____ ppm
CE 370 – Introduction to Environmental Engineering Exam 1 Page 3 of 5 Longer Calculations Questions (5 points each). Problem 6.
(5 points) The national ambient air quality standard for lead (Pb) is 0.15 µg/m
3
. Convert this concentration to units of ppbv assuming 1 atmosphere of pressure and T = 25°C (298 K). The ideal gas constant is 0.082056 (L·atm·mol
-1
·K
-1
). Useful conversion: 1 m
3
= 1000 L. The periodic table is provided on the exam cover. Problem 7.
(5 points) The factory you work at is deciding if it should reduce the amount of vinyl chloride it releases to a river. Decreasing the release by 80% would cost $500,000/day. How many lives would need to be saved per year for this decision to make sense from a risk-benefit-cost analysis perspective? (Assume a life is worth is $7.4 million).
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