Unit C Lesson 6: Human Activities Contribute to Air Pollution
Completion requirements
Unit C Lesson 6: Human Activities Contribute to Air Pollution |
Learning Targets |
Big Question: How do chemicals released from human activities contribute to air
pollution
?
Most air pollutants exist in the environment naturally, but human activity has thrown off nature's balance with dramatic effect.
Most air pollutants exist in the environment naturally, but human activity has thrown off nature's balance with dramatic effect.
At the end of this inquiry, you should be able to answer the following questions:
- Which pollutants affect air quality negatively?
- How is acid rain formed?
- What is ground level ozone?
Pages 225 to 227 your text will help you answer these questions about how human activities contribute to air pollution.
Introduction
Air Pollution
A new factory is planned for your town. You wonder what affect the pollution from the factory will have on peoples’ health over time? What chemicals in the air should be monitored to ensure that air quality in your town remains high?
Since Earth’s creation, harmful chemicals continue to be released into the atmosphere by natural occurrences such as volcanoes and forest fires. However, the largest contributor to air pollution is human activity. When fossil fuels (such as coal, gasoline, oil, and natural gas) are used in power plants, factories, and cars; carbon dioxide, water, and heat are produced.
A new factory is planned for your town. You wonder what affect the pollution from the factory will have on peoples’ health over time? What chemicals in the air should be monitored to ensure that air quality in your town remains high?
Since Earth’s creation, harmful chemicals continue to be released into the atmosphere by natural occurrences such as volcanoes and forest fires. However, the largest contributor to air pollution is human activity. When fossil fuels (such as coal, gasoline, oil, and natural gas) are used in power plants, factories, and cars; carbon dioxide, water, and heat are produced.
The chemical reaction for the burning of a fossil fuel is:
Fossil fuels have impurities. Therefore, dangerous chemicals are released into the atmosphere when fossil fuels undergo combustion (burning).
Sulfur oxides such as sulfur dioxide and sulfur trioxide, nitrogen oxides such as nitrogen monoxide and nitrogen dioxide, carbon dioxide, and ozone are examples of gases that pollute the environment during the burning of fossil fuels.
Sulfur dioxide, sulfur trioxide, and nitrogen dioxide are examples of pollutants that contribute to the formation of acid rain.
fossil fuel + oxygen → carbon dioxide + water + heat
Fossil fuels have impurities. Therefore, dangerous chemicals are released into the atmosphere when fossil fuels undergo combustion (burning).
Sulfur oxides such as sulfur dioxide and sulfur trioxide, nitrogen oxides such as nitrogen monoxide and nitrogen dioxide, carbon dioxide, and ozone are examples of gases that pollute the environment during the burning of fossil fuels.
Sulfur dioxide, sulfur trioxide, and nitrogen dioxide are examples of pollutants that contribute to the formation of acid rain.
Acid rain is also known as acid deposition. When these chemicals combine with water and oxygen in the atmosphere, acids are produced as seen in the equations below:
Sulfuric acid and nitric acids are both strong, harmful acids. When these acids enter the atmosphere, they dissolve in the water in the atmosphere forming acidic vapour.
Eventually, these vapours become part of the clouds, which changes the clouds’ composition, making the cloud more acidic. Nitric acid and sulfuric acid eventually fall back to the Earth's surface as acid deposition.
sulfur dioxide + water + oxygen → sulfuric acid
nitrogen dioxide + water + oxygen → nitric acid
nitrogen dioxide + water + oxygen → nitric acid
Sulfuric acid and nitric acids are both strong, harmful acids. When these acids enter the atmosphere, they dissolve in the water in the atmosphere forming acidic vapour.
Eventually, these vapours become part of the clouds, which changes the clouds’ composition, making the cloud more acidic. Nitric acid and sulfuric acid eventually fall back to the Earth's surface as acid deposition.
Watch
Watch the following video carefully, it does an excellent job of explaining how air pollution can do serious damage to air quality, but also damage water and soil quality as well.
What ingredients produce acid rain? Watch the following video, "Coal Combustion and Acid Rain" for an overview on the development of acid rain.
Acid rain is formed when sulfur oxides and nitrogen oxides, that are produced from factories and cars, combine with water in the atmosphere to produce an acid.
Neutralization Reactions
In 1980, rain in much of North America had a pH similar to that of tomato juice (pH = 4). Industry and automobiles were releasing massive amounts of pollutants, and large cities were smothered in smog. Precipitation has become less acidic since 1980 because many countries put controls on pollutant emissions. However, further improvement is definitely possible.
Recall from Lesson C2, acids have a low pH (pH < 7) and bases have a high pH (pH > 7). When acids and bases react together, neutralization occurs. The products in a neutralization reaction are salts and water, which are both neutral (pH = 7). After a neutralization reaction occurs, the pH of the resulting solution always will be closer to neutral (pH = 7) than it was initially.
In 1980, rain in much of North America had a pH similar to that of tomato juice (pH = 4). Industry and automobiles were releasing massive amounts of pollutants, and large cities were smothered in smog. Precipitation has become less acidic since 1980 because many countries put controls on pollutant emissions. However, further improvement is definitely possible.
Recall from Lesson C2, acids have a low pH (pH < 7) and bases have a high pH (pH > 7). When acids and bases react together, neutralization occurs. The products in a neutralization reaction are salts and water, which are both neutral (pH = 7). After a neutralization reaction occurs, the pH of the resulting solution always will be closer to neutral (pH = 7) than it was initially.
The general equation for neutralization is
One specific example of a neutralization reaction is
hydrochloric acid + potassium hydroxide → potassium chloride + water
(acid) + (base) → (a type of salt) + water
acid + base → salt + water
One specific example of a neutralization reaction is
hydrochloric acid + potassium hydroxide → potassium chloride + water
(acid) + (base) → (a type of salt) + water
Try It!
Practice Worksheet: The Effect of
Neutralization on pH
- DOWNLOAD this practice worksheet (S9_UC_S2_L6_neutralization).
If you prefer to use a Google Drive or PDF version of the worksheet, click here.
-
As you watch the video "Surface Area and Reaction Rate", complete the assessment as indicated on the worksheet.
-
When you are satisfied with your responses you can check your work by clicking on the "SUGGESTED ANSWERS" button below.
Wait! Don't view the suggested answers first. This practice work is not for marks, it is meant to help you check your understanding. Check the answers AFTER doing the questions! Keep the practice worksheet for study purposes. If you don't understand something, contact your teacher!
-
The pH of the cranberry juice before the reaction is 3.7. The pH of the solution increases once Alka-Seltzer is added. The pH of the solution after the neutralization is 5.8.
-
less; The pH of a solution after a neutralization reaction occurs is always closer to neutral (pH=7) than it was originally.
-
cranberry juice (acid) + Alka-Seltzer (base) = salt + water
-
a. composition of the solution, addition of alka-seltzer to the cranberry juice
b. pH
Environmental Effects of Pollution
Lakes and rivers in Western Canada have a much higher pH than lakes and rivers in Eastern Canada because of limestone in the rocks and soil.
Limestone, which is a weak base, reacts with acid deposition to neutralize it. After the reaction with limestone, the deposition has a higher pH that is closer to neutral pH of 7.
limestone + acid rain → salt + water
(base) + (acid) → salt + water
Because acid deposition can be neutralized by the rocks and soil in Alberta, should we bother decreasing the amount of fossil fuels that are being burned by factories and cars? What will happen when all of the limestone in the soil disappears?
Lakes and rivers in Western Canada have a much higher pH than lakes and rivers in Eastern Canada because of limestone in the rocks and soil.
Limestone, which is a weak base, reacts with acid deposition to neutralize it. After the reaction with limestone, the deposition has a higher pH that is closer to neutral pH of 7.
limestone + acid rain → salt + water
(base) + (acid) → salt + water
Because acid deposition can be neutralized by the rocks and soil in Alberta, should we bother decreasing the amount of fossil fuels that are being burned by factories and cars? What will happen when all of the limestone in the soil disappears?
Figure 1 – Western Canada has more limestone than eastern Canada.
Another impact of pollutants released by human activities is how these chemicals affect the ozone layer. High in the atmosphere, the ozone layer protects us from solar radiation. The ozone layer is composed largely of ozone, the oxygen compound
O
3. Chemicals (such as CFCs) that have been released from human activity react with ozone in the upper atmosphere. Efforts to protect the ozone layer by reducing the use of CFCs have been very successful over the past 25 years.
In the lower atmosphere, ozone reacts with other molecules to produce deadly poisons. Ozone (O3 ) is a heavier molecule than atmospheric oxygen (O2) in the air because it contains one extra oxygen atom. If someone breathes ozone at ground level, he will inhale less oxygen into his lungs. This is extremely dangerous in young children, seniors, and people with any breathing difficulties or lung ailments, especially during the summer.
In the lower atmosphere, ozone reacts with other molecules to produce deadly poisons. Ozone (O3 ) is a heavier molecule than atmospheric oxygen (O2) in the air because it contains one extra oxygen atom. If someone breathes ozone at ground level, he will inhale less oxygen into his lungs. This is extremely dangerous in young children, seniors, and people with any breathing difficulties or lung ailments, especially during the summer.
Interactive
Air Pollution
- Click here to watch the BrainPOP video, "Air Pollution", to review what factors can lead to air pollution.
You will need a username and password to access the video.
- Username: 0099
- Password: students
-
Click here
to complete the BrainPOP quiz on Air Pollution. Remember to check your answers at the end!