a Chemical and Engineering News, September 3, 1990, p. 52 Chemistry 431: Environ

Question

a Chemical and Engineering News, September 3, 1990, p. 52
Chemistry 431: Environmental Chemistry
Spring 2016
Skillset Homework
The goal of this assignment is to review some essential skills needed for this course: calculations for
concentration, units conversion and stoichiometry, database searching, and Excel graphing. Show work
for your calculations and justify or cite any assumptions that are made. Submit for a grade by February 5,
2016 by 5:00 PM.
Ideal gas constant = 0.0821 L-atm/mol-K
1.) Assume that the gas phase concentration of sulfur dioxide is measured, and the concentration is 50
g/m3 at 15oC and 1 atm. What is the concentration of SO2 in terms of ppm?
2.) The US Clean Air Act requires the US EPA to set National Ambient Air Quality Standards. Ozone is
one of the pollutants regulated, and the average concentration (as the annual fourth-highest daily
maximum 8-hr concentration, averaged over 3 years) can be no higher than 70 ppb as of October 1, 2015.
What is this concentration in terms of molecules per cubic centimeter at 1 atm and 25oC?
3.) The US Safe Drinking Water Act requires the US EPA regulate contaminates in drinking water.
Bromate ion is a carcinogen that is produced as a by-product of water disinfection, and the bromate ion
concentration in finished drinking water can be no higher than 0.010 mg/L as an annual average.
Calculate the annual average limit for bromate ion in terms of a.) ppb and b.) molarity. Assume that the
density of drinking water is 1 g/mL.
4.) Acid rain has been a point of contention between the US and Canada partly because some of the acid
is the result of sulfur dioxide emissions by coal-fired power plants. The sulfur dioxide dissolves in rain
water and forms sulfuric acid, which decreases the pH of rain water. If the coal that is combusted
averages 2% sulfur by weight, how many metric tons of coal would be required to yield enough H2SO4 to
produce 1 inch of rainfall with a pH of 4.00 over a 104 mile2 area?
5.) Is the following quote correct? Justify your answer quantitatively, and assume that the formula for
gasoline is C9H16 and that combustion is complete.
“One tree can assimilate about 6 kg of CO2 per year or enough to offset the pollution produced by driving
one car for 26,000 miles.” a
6.) If everyone in the world planted a tree today, how long would it take for these trees to decrease the
concentration of CO2 by 1 ppm? Assume that 9 kg of O2 is produced per tree each year regardless of age,
and the CO2 and H2O combine through photosynthesis to form biomass (C6H12O6) and O2. Also assume
that the CO2 that can be assimilated is only in troposphere, which extends 17 km above the surface of the
Earth, and the average temperature and pressure of the troposphere are 273 K and 0.6 atm, respectively.
a Chemical and Engineering News, September 3, 1990, p. 52
7.) Finding articles on environmental chemistry topics is a skill that will be needed for this class. Using
the search term “global climate change,” how many articles can found between using the following three
databases? Note: Both Web of Science and SciFinder Scholar searches must be performed on campus
(i.e., requires computer to have campus IP address).
a.) Web of Science (apps.webofknowledge.com, and enter ‘global climate change’ as a Basic
Search)
b.) Google Scholar (scholar.google.com)
c.) Scifinder Scholar (https://scifinder.cas.org/scifinder/login, you will need to register if haven’t)
8.) Using Scifinder Scholar, prepare column chart in Excel of the number of articles published each year
on the topic of “stratospheric ozone depletion.” To do this, perform the search, select both types of
research topic candidates, and then hit ‘Get References’. Next, on the left side of the screen, in the
Analysis window, select Analyze By/Publication Year. Then select Show More (you may need to scroll
down a little to find this) and another window pops up. Sort by ‘Natural Order’ and then select ‘Export.’
Export the file to a Microsoft Excel format (.xls) which can be viewed in Microsoft Excel and graphed.
Include a copy of the column chart when you submit your assignment for a grade.
After preparing the chart, answer the following questions:
a.) In which year were the most articles published, and how many articles were published that
year?
b.) Looking at the shape of the column chart, there is a second maximum that is smaller than the
main maximum. In what year did this second maximum occur?
9.) Using Web of Science and the search topic term phrase ‘global climate change AND methane
hydrate*’.
a.) Find the article that has been cited by other authors the most number of times. Hint: sorting
by the number of times cited will help you answer this question. How many times has this article
been cited? Write the citation in ACS format as you would see it in the reference list of
Environmental Science & Technology (hint: find an article published in ES&T).
b.) Look at the 17th most cited article on this list, which is an article by Tréhu et al. published in
the Earth and Planetary Science Letters in 2004. Obtain the full text of this article and write the
title of Table 2.
c.) Now sort this list according to ‘Publication Date -- newest to oldest’. Look at the article titled
“Crystal structure, stability and spectroscopic properties of methane and CO2 hydrates”
published in Journal of Molecular Graphics & Modeling in 2013 by Martos-Villa et al. Describe
how you would obtain the full text of this article and estimate how much time it might take to
receive this article.
d.) What is the meaning of the asterisk (*) at the end of hydrate in the search term? In other
words, if you removed the asterisk how will your search results be different?

Explanation / Answer

Answer:

1) 0.0177ppm

2)1.72 x 1012molecules cm3

3):-a) 10ppm

b)

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