Questions and Answers
What do you mean by atmosphere?
The atmosphere is the envelope of gases that surrounds the Earth.
What is the difference between atmosphere and environment?
The atmosphere specifically refers to the layer of gases surrounding the Earth, while the environment encompasses all living and non-living things in a given area including air, water, and land.
Name the major constituents of the troposphere.
Nitrogen and oxygen constitute about 99% by volume of the Earth's atmosphere.
How is the temperature of the atmosphere maintained?
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Where does the ozone layer exist?
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Why is the temperature of the upper stratosphere higher?
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What do you mean by an air pollutant?
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Name three primary air pollutants.
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Identify as primary or secondary air pollutant: SO2, CH4, HNO3, NH3, H2SO4, O3.
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Why is CO2 called a greenhouse gas?
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Why are flood risks increasing?
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Comment: burning in open air is preferred.
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How are sulfur-containing compounds emitted naturally?
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How does combustion of fossil fuels in internal combustion engines produce oxides of nitrogen?
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How is acid rain produced?
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Why does acid rain damage buildings?
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How is aquatic life affected by acid rain?
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Why are plants dying day by day?
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Justify why ozone is beneficial for humankind.
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Why is ozone depleting in the atmosphere?
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What do you mean by ozone hole?
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Where is the ozone layer found?
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Explain the phenomenon of decreasing temperature in the troposphere.
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Differentiate between primary and secondary air pollutants.
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State the major sources of CO and CO2 emission.
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How is CO2 responsible for heating up the atmosphere?
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CO is a hidden enemy, explain its action.
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What threats are there to human health due to SO2 gas as an air pollutant?
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Which air pollutant is produced on anaerobic decomposition of organic matter?
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How does acid rain increase the acidity of soil?
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Point out two serious effects of ozone depletion.
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How is the ozone layer formed in the stratosphere?
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Why does 75% of the atmospheric mass lie within the troposphere?
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How is the ozone layer being depleted by chlorofluorocarbons?
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Write down the significance of atmospheric gases.
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Give the characteristics of troposphere. Why does temperature decrease upwards in this sphere?
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What are the characteristics of the stratosphere? Why does temperature increase upwards in this sphere?
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CO2 is necessary for plants but why is its increasing concentration alarming for us?
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Why is CO considered a health hazard?
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Define acid rain. How is it formed and what are its effects?
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Compounds of sulphur are air pollutants. Describe the sources of these compounds along with their effects.
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Where does the ozone layer lie in the atmosphere? How is it depleting and how can we prevent its depletion?
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Oxides of nitrogen cause air pollution. Describe the sources of these compounds.
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Study Notes
Environmental Chemistry I: The Atmosphere
Composition of Atmosphere
- The atmosphere is an envelope of different gases around the Earth
- About 99% of atmospheric mass lies within 30 kilometers of the surface
- The atmosphere is divided into four regions: troposphere, stratosphere, mesosphere, and thermosphere
- Percentage composition of atmosphere by volume:
- Nitrogen: 78.09%
- Oxygen: 20.94%
- Argon: 0.93%
- Carbon dioxide: 0.03%
Layers of Atmosphere
- Troposphere: extends up to 12 km, temperature decreases regularly from 17°C to -58°C
- Stratosphere: extends up to 50 km, temperature rises gradually up to 2°C
- Mesosphere: covers up to 85 km, temperature decreases down to -93°C
- Thermosphere: temperature increases upwards
Characteristics of Troposphere and Stratosphere
- Troposphere:
- Major constituents: nitrogen and oxygen gases
- Carbon dioxide and water vapors play a significant role in maintaining temperature
- Temperature decreases at a rate of 6°C per kilometer
- Stratosphere:
- Presence of ozone (due to absorption of radiation) is responsible for the rise of temperature
- Ozone layer exists in mid-stratosphere
Air Pollutants
- Three factors determine the severity of a pollutant: chemical nature, concentration, and persistence
- Types of pollutants:
- Primary pollutants: waste products driven out due to combustion of fossil fuels and organic matter (e.g. oxides of sulfur, carbon, and nitrogen, hydrocarbon, ammonia, and compounds of fluorine)
- Secondary pollutants: produced by various reactions of primary pollutants (e.g. sulfuric acid, carbonic acid, nitric acid, hydrofluoric acid, ozone, and peroxyacetyl nitrate)
- Sources of air pollutants:
- Oxides of carbon (CO2 and CO): combustion of fossil fuels, decomposition of organic matter, and volcanic eruptions
- Oxides of sulfur (SO2 and SO3): combustion of fossil fuels, decomposition of organic matter, and volcanic eruptions
- Oxides of nitrogen (NOx): combustion of fossil fuels, decomposition of organic matter, and electrical lightening in air
Effects of Air Pollutants
- CO: highly poisonous, binds with haemoglobin, hindering oxygen supply to the body
- CO2: contributes to greenhouse effect and global warming
- SO2: forms sulfuric acid, damages buildings and vegetation, and causes respiratory problems
- NOx: forms nitric acid, contributes to acid rain, and irritates breathing passage
Control of Air Pollution
- Role of government: improve fuel quality, make combustion engines efficient, and preserve the natural environment### Air Pollution and Its Effects
- Burning of fossil fuels produces air pollutants, such as oxides of sulphur and nitrogen, which contribute to acid rain formation.
- Government should promote the use of alternative fuels, such as methanol, ethanol, and bio-diesel, which are less polluting than hydrocarbons.
- Battery-powered electric vehicles can reduce carbon dioxide production, a greenhouse gas.
Acid Rain and Its Effects
- Acid rain is formed when rain water dissolves acidic air pollutants, such as sulphur dioxide and nitrogen dioxide, reducing the pH of rain water to 4.
- Effects of acid rain include:
- Leaching heavy metals into soil and water, affecting human health and aquatic life.
- Damaging buildings and monuments by reacting with calcium carbonate.
- Increasing soil acidity, affecting plant growth and tree health.
- Directly damaging leaves and limiting plant growth.
Ozone Depletion and Its Effects
- Ozone (O3) is an allotropic form of oxygen, formed in the atmosphere by the association of an oxygen atom with an oxygen molecule.
- Ozone layer, present in the stratosphere, protects the Earth from harmful ultraviolet radiations of sunlight.
- Chlorofluorocarbons (CFCs) are the major cause of ozone layer depletion, reacting with ozone to form oxygen and chlorine free radicals.
- Effects of ozone depletion include:
- Increased risk of skin cancer and infectious diseases.
- Disruption of the food chain and climate changes.
Incineration of Waste Material
- Incineration reduces the volume of solid waste by 80-85%, but produces poisonous gases and toxic ash, including dioxins, furans, and particulate matter.
- Key air pollutants from incineration include sulphur dioxide, carbon dioxide, carbon monoxide, and hydrochloric acid.
Filtration of Suspended Impurities
- Filtration separates insoluble solid particles from a liquid using a filter paper, with the mixture being poured into the filter paper and the filtrate being collected in a conical flask.
- The solid particles deposit on the filter paper and are dried, leaving a residue.
Atmosphere and Air Pollutants
- Atmosphere is divided into four regions: troposphere, stratosphere, mesosphere, and thermosphere.
- Natural sources of air pollutants include volcanic eruptions and decomposition of organic matter.
- Human activities, such as burning fossil fuels, open air fires, and forest fires, contribute to air pollution.
- CO2 forms a layer around the Earth, absorbing infrared radiations and causing the greenhouse effect.
- CO is highly poisonous and a health hazard, while SO2 is also a health hazard and forms sulphuric acid by combining with water vapours in air, contributing to acid rain.
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Description
Learn about the atmosphere, its composition, and the difference between stratosphere and troposphere. This quiz covers the basics of environmental chemistry.