Barcode:
SCHOOL OF CHEMISTRY & PHYSICS
UNIVERSITY OF KWAZULU-NATAL, WESTVILLE CAMPUS
APCH 211: ENVIRONMENTAL CHEMISTRY
NOVEMBER 2014 MAIN EXAMINATION
Duration: 3 hours; 100 marks
Student No.
Seat Number:
Instructions:
1.
2.
3.
4.
5.
6.
7.
Answer ALL Questions
Calculators may be used but all workings must be shown, where applicable
You must write legibly in black or blue ink. Pencil and Tipp-EXTM are not allowed
Answers must be written on the question paper in the space provided
The blank side may be used for extra space or rough work (indicate where appropriate)
The pages of the exam paper must not be separated
There are 5 pages in total in Section A and a cover page; check that you have them all.
Internal Examiners:
Internal Moderator:
Dr PG Ndungu & Dr K Pruessner (UKZN-WVL)
Dr N Nombona (UKZN-WVL)
SECTION A: Chemistry of the Lithosphere
Total
Total
A2
A3
A4
A5
A6
A7 Section Section
A
B
Question
A1
TOTAL
Internal
Marks
6
5
3
13
5
5
3
40
60
100
External
Marks
6
5
3
13
5
5
3
40
60
100
Rule 9 (1)(e) WARNING: CANDIDATES WILL BE DISQUALIFIED IF:
(a) they introduce, or attempt to introduce, into any place where an examination is about to be conducted or is being conducted, any paper, book,
note, document or instrument, the use of which is not authorized by the examiner or the examination officer.
(b) they possess, use, or attempt to use during an examination, any paper, book, note, document or instrument the use of which is not authorized by
the examiner or the examination officer.
(c) they remove or attempt to remove from the examination room, any examination book or writing paper supplied by the University for the
purposes of answering an examination.
(d) they communicate or attempt to communicate any information relating to the examination to another candidate while the examination is in
progress.
(e) they use a false name or identity number in an examination.
(f) they commit any other fraudulent, deceitful or dishonest practice which would mislead or deceive the examiner or examination officer.
IF A STUDENT IS FOUND GUILTY BY A STUDENT DISCIPLINE COURT OF CONTRAVENING THE ABOVE RULE –9(1)(e) – SHE/HE WILL SUFFER ONE OR
MORE OF THE FOLLOWING CONSEQUENCES:
(i) Disqualification from entry to any examination.
(ii) Cancellation or forfeiture of examination results.
(iii) Deprivation of a degree, diploma or certificate obtained as a result of the offence.
University of KwaZulu-Natal, School of Chemistry and Physics, Westville Campus
November 2014 Main Examination Session, APCH 211 Environmental Chemistry
Section A: Chemistry of the Lithosphere
Question A1
Draw a sketch that shows the formation of new crust and the subduction of old crust on earth.
Indicate where these processes occur.
[6 points]
Question A2
Show that the condition for a cubic coordination in ionic crystals is r/R > 0.733. Include a labelled
drawing in your answer.
[5 points]
Page | 1 University of KwaZulu-Natal, School of Chemistry and Physics, Westville Campus
November 2014 Main Examination Session, APCH 211 Environmental Chemistry
Question A3
What are the 3 classes of sedimentary rocks? Name an example for each one.
[3 points]
Question A4
(a)
Igneous rocks are further classified according to the amount of the 4 main minerals
comprising them. Draw the complete Q-A-F-P diagram for volcanic rocks and indicate the
fields for basalt and rhyolite.
(6)
Page | 2
University of KwaZulu-Natal, School of Chemistry and Physics, Westville Campus
November 2014 Main Examination Session, APCH 211 Environmental Chemistry
Question A4 continued
(b)
What do the letters Q, A, F and P stand for ?
(2)
(c)
What class of minerals are they?
(1)
(d)
What is their percentage range in basalt and rhyolite ?
(4)
[13 points]
Page | 3
University of KwaZulu-Natal, School of Chemistry and Physics, Westville Campus
November 2014 Main Examination Session, APCH 211 Environmental Chemistry
Question A5
(a)
Name at least 6 important properties of soils.
(3)
(b)
What is the particle size range in a typical soil ?
(2)
[5 Points]
Question A6
(a)
What is mercury used for in mininig operations ?
(3)
Page | 4
University of KwaZulu-Natal, School of Chemistry and Physics, Westville Campus
November 2014 Main Examination Session, APCH 211 Environmental Chemistry
Question A6 continued
(b)
What environmental hazards are involved in the use of mercury ?
(1)
(c)
What is an alternative to the use of mercury ?
(1)
[5 Points]
Question A7
Explain why clay-rich soils have desirable physical and chemical properties for use as liners for
landfill sites.
[3 points]
TOTAL: 40 points
END SECTION A:
Chemistry of the Lithosphere
Page | 5
Barcode:
SCHOOL OF CHEMISTRY & PHYSICS
UNIVERSITY OF KWAZULU-NATAL, WESTVILLE CAMPUS
APCH 211: ENVIRONMENTAL CHEMISTRY
NOVEMBER 2013 MAIN EXAMINATION
Duration: 3 hours; 100 marks
Student No.
Seat Number:
Instructions:
1.
2.
3.
4.
5.
6.
7.
Answer ALL Questions
Calculators may be used but all workings must be shown, where applicable
You must write legibly in black or blue ink. Pencil and Tipp-EXTM are not allowed
Answers must be written on the question paper in the space provided
The blank side may be used for extra space or rough work (indicate where appropriate)
The pages of the exam paper must not be separated
There are 10 pages in total in Section B, along with a cover page, a periodic table, and a data sheet;
check that you have them all.
Internal Examiners:
Internal Moderator:
Dr PG Ndungu & Dr K Pruessner (UKZN-WVL)
Dr BO Owaga (UKZN-WVL)
SECTION B: Chemistry of the Atmosphere and the Hydrosphere
Total
Question
B1
B2
B3
B4
B5
B6
Section B
Internal
Marks
10
5
15
15
10
5
60
External
Marks
10
5
15
15
10
5
60
TOTAL
100
100
Rule 9 (1)(e) WARNING: CANDIDATES WILL BE DISQUALIFIED IF:
(g) they introduce, or attempt to introduce, into any place where an examination is about to be conducted or is being conducted, any paper, book,
note, document or instrument, the use of which is not authorized by the examiner or the examination officer.
(h) they possess, use, or attempt to use during an examination, any paper, book, note, document or instrument the use of which is not authorized by
the examiner or the examination officer.
(i) they remove or attempt to remove from the examination room, any examination book or writing paper supplied by the University for the
purposes of answering an examination.
(j) they communicate or attempt to communicate any information relating to the examination to another candidate while the examination is in
progress.
(k) they use a false name or identity number in an examination.
(l) they commit any other fraudulent, deceitful or dishonest practice which would mislead or deceive the examiner or examination officer.
IF A STUDENT IS FOUND GUILTY BY A STUDENT DISCIPLINE COURT OF CONTRAVENING THE ABOVE RULE –9(1)(e) – SHE/HE WILL SUFFER ONE OR
MORE OF THE FOLLOWING CONSEQUENCES:
(iv) Disqualification from entry to any examination.
(v) Cancellation or forfeiture of examination results.
(vi) Deprivation of a degree, diploma or certificate obtained as a result of the offence.
University of KwaZulu-Natal, School of Chemistry and Physics, Westville Campus
November 2014 Main Examination Session, APCH 211 Environmental Chemistry
Section B: Chemistry of the Atmosphere and the Hydrosphere
Question B1
The smoking area for a local bar (dimensions 7.5 m x 12 m x 2.5 m) has 12 people in the
room, and two thirds of the people are smoking on average 5 cigarettes per hour. Each
cigarette when smoked releases 1.85 mg of formaldehyde (H2CO). The ventilation system
exchanges the air in the smoking room 3 times every hour with the outside of the bar.
(a)
Assuming that the concentration of formaldehyde in the main part of the bar is
negligible, calculate the steady state concentration of formaldehyde inside the
smoking room and provide your final answer in ppbv.
(8)
Page | 1
University of KwaZulu-Natal, School of Chemistry and Physics, Westville Campus
November 2014 Main Examination Session, APCH 211 Environmental Chemistry
Question B1 continued
(b)
Recommended air quality guideline for formaldehyde is 0.1 mg m-3 for a 30 minute
exposure limit. Comment on whether the smokers are at risk?
(1)
(c)
If the smokers are at risk, what would you recommend the owner does to reduce their risk
levels (note telling the smokers to quit smoking is not an option)?
(1)
[10 points]
Question B2
The following questions refer to water quality parameters.
(a)
Define BOD.
(1)
Page | 2
University of KwaZulu-Natal, School of Chemistry and Physics, Westville Campus
November 2014 Main Examination Session, APCH 211 Environmental Chemistry
Question B2 continued
(b)
Define COD.
(1)
(c)
In terms of water quality parameters, why is the level of dissolved oxygen content
important and how is it related to COD?
(3)
[5 points]
Question B3
(a)
When considering the earth’s atmosphere, where is the Mesopause located?
(1)
Page | 3
University of KwaZulu-Natal, School of Chemistry and Physics, Westville Campus
November 2014 Main Examination Session, APCH 211 Environmental Chemistry
Question B3 continued
(b)
Why does the concentration of ozone peak in the mid region of the stratosphere?
(4)
(c)
chlorodifluoromethane, CHF2Cl (HCFC-22), is a hydrochlorofluorocarbon that was
introduced about four decades ago to replace CFC-11 and CFC-12. What are the
IUPAC names and structural formula’s for CFC-11 and CFC-12?
(2)
Page | 4
University of KwaZulu-Natal, School of Chemistry and Physics, Westville Campus
November 2014 Main Examination Session, APCH 211 Environmental Chemistry
Question B3 continued
(d)
Why were CFC’s banned and which international treaty has led to the complete
phase out of CFC’s.
(2)
(e)
Page | 5
What is the minimum wavelength of electromagnetic radiation that can initiate the
following reaction (provide your answer in nm)?
ΔH = 366.1 kJ mol-1
CHF2Cl  CHF2 + Cl
(3)
University of KwaZulu-Natal, School of Chemistry and Physics, Westville Campus
November 2014 Main Examination Session, APCH 211 Environmental Chemistry
Question B3 continued
(f)
Which layer in the atmosphere would you expect this reaction to take place, and
explain why CHF2Cl (HCFC-22) can be a viable substitute for CFCs?
(3)
[15 points]
Question B4
(a)
Define acidic precipitation and name the region of atmosphere it usually occurs.
(2)
(b)
List two nitrogen species and two sulfur species that are responsible for acidic
precipitation.
(4)
Page | 6
University of KwaZulu-Natal, School of Chemistry and Physics, Westville Campus
November 2014 Main Examination Session, APCH 211 Environmental Chemistry
Question B4 Continued
(c)
What detrimental effects could be observed with acidic precipitation on lakes,
farmland, and a major city like Durban?
(4)
(d)
Using suitable balanced equations, summarize the production of nitric acid, in the
troposphere, at 20h00 (8 pm) over the city of Durban.
(5)
[15 points]
Page | 7
University of KwaZulu-Natal, School of Chemistry and Physics, Westville Campus
November 2014 Main Examination Session, APCH 211 Environmental Chemistry
Question B5
Endosulfan (C9H6Cl6O3S) is a well-known pesticide used in agriculture to control insect
infestations during the growing season. The chemical will be added to the list of POPs
under the Stockholm Convention.
(a)
What is the Stockholm Convention?
(1)
(b)
You are tasked with monitoring the levels of Endosulfan in a well-known dam in the
KZN midlands. You sample the water from the dam every two months for two years,
and determine the values of Endosulfan were 458.7, 359.5, 281.7, 220.8, 173.0,
135.6, 106.3, 83.3, 65.3, 51.2, 40.1, 31.4, and 24.6 ng mL-1. What is the half-life of
the removal process for the pesticide?
(4)
Page | 8
University of KwaZulu-Natal, School of Chemistry and Physics, Westville Campus
November 2014 Main Examination Session, APCH 211 Environmental Chemistry
Question B5 continued
(c)
The USEPA water quality guidelines recommend that the level of Endosulfan should
be 0.056 ng mL-1 in aquatic environments. Assuming Endosulfan is banned and never
used again in South Africa, how many years will it take until the levels of
Endosulfan in the Dam reach a safe level?
(2.5)
(d)
Carp fish in the dam can typically weigh 18.25 kg or more, a recent study by UKZN
postgraduate students found that the fish has an average concentration of 395 μg/ Kg. The
USEPA's acute reference dose for dietary exposure to endosulfan is 0.015 mg/kg for adults
and 0.0015 mg/kg for children. What is maximum mass of fish a 70 kg adult and a 30 kg
child can eat in one day?
(2.5)
[10 points]
Page | 9
University of KwaZulu-Natal, School of Chemistry and Physics, Westville Campus
November 2014 Main Examination Session, APCH 211 Environmental Chemistry
Question B6
(a)
Name four industrial scale systems used to control particulate matter emissions
from a process.
(2)
(b)
What is underground
disadvantages.
coal
gasification
and
describe
its
advantages
and
(3)
[5 points]
TOTAL: 60 points
END SECTION B
Chemistry of the Atmosphere and the Hydrosphere
Page | 10