IB SL Chemistry

Option E: Environmental Chemistry

Student Workbook

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IB SL Chemistry - Option E: Environmental Chemistry

Instructions: Complete all questions in each section, using the references listed. You will need

Internet access, Derry, et.al. Chemistry Options: SL and HL and this booklet to complete the topic.

1. http://en.wikibooks.org/wiki/IB_Chemistry/Environmental_Chemistry

2. http://www2.sd35.bc.ca/teachers/aklassen/klassens_Science_Page/IB_Chemistry_files/IB%20

Chem%20environmental%20notes.pdf

3. http://chemactive.com/ib.html

E1: Air Pollution

1. What is „primary‟ air pollution? „Secondary‟ air pollution?

2. What are the pollutants that contribute most to air pollution?

E.1.1 Describe the main sources of carbon monoxide (CO), oxides of nitrogen (NOx), oxides of

sulfur (SOx), particulates and volatile organic compounds (VOCs).

Carbon monoxide: 1. Draw a Lewis dot diagram of carbon monoxide.

2. Write the balanced chemical equation of methane reacting with oxygen to produce carbon

monoxide and water.

3. List the natural sources of CO:

4. List the anthropogenic sources of CO:

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Nitrogen:

1. Name 3 sources of nitrogen oxides in the atmosphere?

a. Draw the Lewis dot diagram for all 3 sources

b. Which of the 3 sources are primary pollutants and which are secondary?

c. Write all chemical equations for the production of the primary pollutants.

d. Write all chemical equations for the production of the secondary pollutants.

2. Natural sources:

3. Anthropogenic sources:

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Sulfur:

1. How is sulfur trioxide produced? Write a chemical equation to back up your findings.

2. List and explain the 3 principal sources of sulfur oxides. Write a chemical equation for each

source.

Particulates:

1. List the natural sources:

2. List and explain anthropogenic sources:

Volatile Organic Compounds (VOCs)

1. Natural sources of VOCs:

2. Anthropogenic Sources:

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E.1.2 Evaluate current methods for the reduction of air pollution.

Refer to Derry, et.al. as well as online resources. Make sure to read the syllabus for further

instruction.

1. Which primary pollutants can be caused by vehicle exhaust?

2. For each of the following methods, state which pollutant(s) it decreases and describe how it

works:

a. Lean Burn Engines http://www.indiacar.com/infobank/lean_burn_engine.htm

i. What are lean combustion engines designed for?

b. Catalytic Converters http://auto.howstuffworks.com/catalytic-converter.htm

i. List three important catalysts used in catalytic converters.

c. Scrubbers http://en.wikipedia.org/wiki/Scrubber

i. Describe the difference between wet and dry scrubbers

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d. Fluidized Bed Combustion http://www.wordiq.com/definition/Fluidized_bed_combustion

e. Electrostatic precipitation

f. What are some other methods that can be used to remove sulfur from coal and oil

reduce oxides or sulfur in the atmosphere?

E.2 Acid Deposition

E.2.1 State what is meant by the term acid deposition and outline its origins.

1. Using your previous knowledge of acids and bases, predict what is meant by acid rain

2. Most of us would believe natural rainfall to be neutral, but in fact it is considered slightly acidic.

What causes this slight acidity and what is the approximate pH value of natural rain?

3. Carbon dioxide itself does not cause acidity in the atmosphere. It reacts with the water vapor in the

atmosphere to yield a weak carbonic acid. Write a balanced equation for this reaction.

4. Which two gases resulting from combustion are primarily responsible for acid rain?

i.

ii.

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5. Go to http://www.ec.gc.ca/air/default.asp?lang=En&n=7E5E9F00-1 and scroll down until you see

two pie charts of NOx emissions

What was the major source of NOx in the following countries:

Canada? and what was the percentage? ___ %

USA? and what was the percentage? ___ %

Thus, the major source of NOx is: ________________________

6. Observe the other pie charts on this site, and deduce the major anthropogenic (man made) source

of SO2

Source: ___________________

7. As mentioned previously, these gases result from combustion reactions. Use stoichiometry to

balance the following reactions:

_N2(g) + _O2(g) _NO2(g)

_S(s) + _O2(g) _SO2(g)

8. Gaseous products of the previous combustion reactions react with water vapor in the atmosphere to

yield two strong acids, one monoprotic & one diprotic. What are these two acids?

i) _____________________ & ii) ________________________

9. Write a chemical equation for each gas to yield the acidic solutions in #8.

i)

ii)

10. NOx and SOx can form weak acids as well. Write the chemical equation for each gas to yield a

weak acidic solution.

Eq 1:

Eq 2:

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E.2.2 Discuss the environmental effects of acid deposition and possible methods to counteract

them.

1. http://geography.about.com/od/globalproblemsandissues/a/acidrain.htm follow this link to outline

4 major areas affected by acid rain.

2. Why is it more probable for a lake to be affected by acid rain in comparison to flowing water, such

as rivers or streams?

3. Look at the picture below, and deduce two possible effects of acid rain that can be seen

i.

ii.

4. Metals are known to react in the presence of an acid. Knowing this property, why would the

combination of acid rain and household water pipes be bad or even lethal?

Hint: Plumbers repair pipes. What element do the letters Pb represent?

FYI: In some countries, copper has replaced this metal in pipes to reduce toxicity.

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5. The following chart shows pH ranges a marine organism can withstand.

Look back at question 2 and explain briefly why acid rain will be deadly in a still body of

water, such as a lake containing these organisms.

6. Structures such as the Capital Building in Washington D.C, and the Parthenon in Greece have

somewhat lost their structural shape. Acid rain is known to have a part in their degradation as marble

is composed of calcium carbonate. Write a balanced equation that explains the effects of a sulfuric

acid on marble, and include their physical states.

Looking at the resulting products, what other “environmental” problem can result from this reaction?

Hint: Pay attention to the gaseous products.

7. Using the answers you‟ve provided so far, come up with at least two possible ways of

counteracting the effects of acid rain. Think back to the four major areas affected by the acid rain.

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E.3 Greenhouse Effect

E.3.1 Describe the greenhouse effect.

1. What is the greenhouse effect?

2. How does it affect the Earth‟s temperature?

3. Why is this necessary to biological organisms?

4. Describe the enhanced greenhouse effect?

5. Draw a model illustrating the greenhouse effect

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E.3.2 List the main greenhouse gases and their sources, and discuss their relative effects

1. What makes a gas a greenhouse gas?

2. Which gas is the single largest contributor to the greenhouse effect?

3. What evidence is there to suggest that human activity is responsible for the enhanced greenhouse

effect and global warming?

4. What anthropogenic gas is the major contributor to the greenhouse effect?

5. Complete this table of the main greenhouse gases, listing their sources and discussing the effects of

each.

Gas Sources Global warming

potential

Contribution to Global

Warming

CO2

N2O

CH4

H2O

O3

CFC‟s

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E.3.3 Discuss the influence of increasing amounts of greenhouse gases on the atmosphere.

1. Write a paragraph discussing the effects of greenhouse gases increasing using the following

phrases: thermal expansion of the oceans, melting of the polar ice-caps, floods and drought, changes

in precipitation and temperature, changes in the yield and distribution of commercial crops, and

changes in the distribution of pests and disease-carrying organisms.

E.4 Ozone depletion

E.4.1 Describe the formation and depletion of ozone in the stratosphere by natural processes.

a. What is ozone?

b. Where is the ozone layer located?

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c. Write two equations that occur during the natural formation of Ozone. What is the role of UV

in this process? (Refer to figure below)

d. Ozone is destroyed naturally in the environment. Write the reactions for the natural

destruction of ozone. Where does the energy come from to break the bonds in the ozone?

e. Which requires more energy, the breaking of an O2 molecule or the breaking of an O3

molecule? Explain.

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E.4.2 List the ozone-depleting pollutants and their sources. Refer to the website:

http://www.atm.ch.cam.ac.uk/tour/index.html

a. How did we find out the amount of ozone in the ozone layer has been decreasing?

b. What is the main cause of the decrease in ozone?

c. What is a CFC? What are its components?

d. What properties of CFC‟s lead to ozone depletion and how? (See figure 2)

e. Other substances that damage the ozone layer are oxides of nitrogen. What are the manmade

sources of these compounds?

Figure 2: Life Cycle of CFC's

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E.4.3 Discuss the alternatives to CFCs in terms of their properties

a. List some substances that can be used as alternatives of CFC‟s.

b. What properties should these alternatives have?

c. The most important replacements are HCFC‟s hydro fluorocarbons. What are the properties that

make them a good alternative? Give examples.

E.5 Dissolved Oxygen in Water

1. Dissolved oxygen (DO) is vital for the survival of aquatic organisms. Using the following website,

http://www.waterontheweb.org/under/waterquality/oxygen.html , explain the reasons why living

organisms need oxygen to survive. Define the term “DO”.

E.5.1 Outline biological oxygen demand (BOD) as a measure of oxygen-demanding wastes in

water.

Refer to Derry et.al.

1. Define Biochemical oxygen demand (BOD).

2. Water that has a high BOD without adequate means of replenishing oxygen will cause aquatic life

to die. Using this information, deduce which kind of water bodies (e.g. lakes, rives etc.) can afford to

have a high BOD. (**hint: think about rate of water flow).

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E.5.2 Distinguish between aerobic and anaerobic decomposition of organic material in water.

1. Outline the difference between aerobic and anaerobic decomposition and state the requirements

needed for each to take place.

2. Aerobic and anaerobic decomposition produces different types of products depending on the

element that is decomposed. Fill in the following table: Refer to p.110 in your study guide.

Element Aerobic

Decay

Product

Anaerobic

Decay

Product

Example reaction:

aerobic or anerobic?

oxidation numbers – redox?

Carbon

Hydrogen

Sulfur

Phosphorus

E.5.3 Describe the process of eutrophication and its effects

1. Nitrates and phosphates found in fertilizers are used to boost the growth of plants. However, large

amounts of these chemicals can have an adverse effect on the life of organisms in the water. Define

eutrophication. Draw a flow diagram explaining how nitrates and phosphates lead to eutrophication.

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E.5.4 Describe the source and effects of thermal pollution in water. 1. The solubility of oxygen in water depends on temperature.

Outline what happens to the level of oxygen saturation as the

temperature is changed and how these temperature changes can

occur.

2. Metabolism of fish is affected by a change in temperature. Outline the effects of temperature on

the metabolism of fish.

E.6 Water Treatment

E.6.1 List the primary pollutants found in waste water and identify their sources.

Primary Pollutant Source of Pollutant

Heavy metals

Pesticides

Dioxins

Polychlorinated biphenyls

(PCBs)

Organic matter

Nitrates and phosphates

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E.6.2 Outline the primary, secondary and tertiary stages of waste water treatment and state the

substance that is removed during each stage.

1. Describe primary, secondary and tertiary treatments and make reference to the diagram of a

general sewage treatment process above. Also good diagrams in Derry, et.al.

Primary:

Secondary:

Tertiary:

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2. What waste product(s) are removed at each stage?

E.6.3 Evaluate the process to obtain fresh water from sea water using multistage distillation

and reverse osmosis.

Process to

make fresh

water

How does it work? Benefits Limitations

Multistage

distillation

Reverse

Osmosis

Reverse osmosis

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E.7 Soil

Refer to Derry, et.al. starting on page 292 to answer these

introductory questions.

1. What is soil degradation?

2. What are the natural and anthropogenic causes of soil degradation?

3. What are the two main soil nutrient groups?

E.7.1 Discuss salinization, nutrient depletion and soil pollution as causes of soil degradation.

(Be sure to read the syllabus about this assessment statement – a wealth of information)

1. What is salinization?

2. Which salts are typically found in irrigated soil?

3. What events cause salinization?

4. How does salinization affect plant growth?

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5. Write a paragraph explaining nutrient depletion.

6. Explain how each of the following pollutes or contaminates the soil:

i. Pesticides

ii. Herbicides

iii. Fungicides

iv. Fertilizers

v. Domestic and industrial waste

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E.7.2 Describe the relevance of the soil organic matter (SOM) in preventing soil degradation

and outline its physical and biological function. (Be sure to read the assessment statement in the

syllabus)

1. Define soil organic matter (SOM).

2. How can the organic carbon be determined in the soil?

3. What is included in soil organic matter?

4. What is the main importance of soil organic matter?

(HINT: Ions)

5. Biological: What 3 mineral nutrients (i.e. elements) are available in soil organic matter AND what

role do they have in plants?

6. Physical: Why is soil organic matter physically important?

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E.7.3 List common organic soil pollutants and their sources.

Common Organic Soil Pollutants Source

E.8 Waste

E.8.1 Outline and compare the various methods for waste disposal

Consider cost, land use, environmental impact/pollution

Advantages Disadvantages

Landfills

Incineration

Ocean

Dumping

Recycling

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E.8.2 Describe the recycling of metal, glass, plastic, and paper products, and outline its benefits.

Recycling Process Benefits

Metals

Glass

Plastics

Paper

E.8.3 Describe the characteristics and sources of different types of radioactive

waste.

1. What is radioactive waste?

2. List and explain the 3 common types of radioactive emissions.

3. Define half-life of a radioactive substance.

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4. Explain how to calculate the half-life of Pu-239 after 1 half-life, 2 half-lives

and seven half-lives.

E.8.4 Compare the storage and disposal methods for different types of radioactive waste.

1. Radioactive storage and disposal depends on what?

2. Describe in detail how low level radiation is stored and disposed. Give examples.

3. Describe in detail how high level radiation is stored and disposed. Give examples.