Explain how the greenhouse gases carbon dioxide and methane cause global warming, some example include: (a) the absorption, reflection, and emission of thermal energy. (b) reducing thermal energy loss to space. Describe the role of sulphur in the formation of acid rain and its impact on the environment.
Describe the strategies to reduce the effect of environmental issues. Some examples include (a) climate change: planting trees, reduction in livestock farming, decreasing use of fossil fuels, increasing use if hydrogen, and renewable energy, e.g., wind, solar (b) acid rain: use of catalytic converters in vehicles, reducing emissions of sulphur dioxide by using low sulphur fuels and flue gas desulphurization with calcium oxide.
Describe the role of NO and NOx in the formation of acid rain, both directly and through their catalytic role in the oxidation of atmospheric sulphur dioxide. Explain how oxides of nitrogen form in car engines and describe their removal by catalytic converters, e.g. CO-2NO → 2CO+N.
Define photosynthesis as the reaction between carbon dioxide and water to produce glucose and oxygen in the presences of chlorophyll and using energy from sun.
Analyze how to use tools to reduce personal exposure to harmful pollutants (some examples include the usage of masks, air quality indices and CO detectors).
Identify high risk situations in life including those where long-term exposure to these pollutants can lead to respiratory issues and reduction in quality and longevity of life.
This chapter will help you understand what atmosphere means. How the atmosphere is polluted and what substances pollute it? It is also necessary to understand the sources of general air pollution and the harmful effects on living things and the environment. You start your day with a cup of tea, which is a mixture of water, milk, tea, fat, and sugar. The same applies to milk, which is a mixture of water, minerals, proteins, vitamins, and fats. If scum or impure ingredients are added, the tea or milk is contaminated and unhealthy to drink. Air is a mixture of various gases including nitrogen, oxygen, hydrogen, carbon dioxide, noble gases, and water vapor. The summer season is getting longer and hotter all over the world compared to ten years ago, why? You also know why iron nails rust faster in rainwater than in tap water or mineral water.
Air is a mixture of gases. Can you name the main gases that make up the air? The pie chart given below shows the composition of dry air by volume. (Figure 11.1)
Composition of Dry Air
Other gases
S by volume
0.93
Argon
0.035
Carbon
dioxide
Neon
Helium
0.0018
0.00052
0.00015
0.00013
Methane
Krypton
Hydrogen
21% Oxygen
Other gases
0.00003
Besides gases, there are varying amounts of water vapour in the air. There is little water in the air over the desert amounts in the tropical rainforest, the air may contain little water in the air. This means the amount of water vapour in the air varies from place to place and from time to time. The envelope of gases and water vapour surrounding the planet Earth is called the atmosphere.
What two gases make up most of the air?
Think of a situation when you are in a park or a vegetable farm and in second case you are near a kiln or a garbage dump. Where would you feel fresh?
Pollutants are things like industrial wastes, herbicides, pesticides, insecticides, particles of dust. and smoke, carbon monoxide, nitrogen dioxide, sulphur dioxide, ozone and lead containing paints. These things have a negative impact on the environment. Such substances effect environment as a result of human activity. Anything that is in the air, water or soil which has a harmful effect on some part of the environment is called pollutant. Pollutants damage the environment, health and quality of life. Important air pollutants are as follows:
You might have noticed that the colour of silk clothes fades away, if left in open air for a week or so. What due to it is?
Sulphur is found naturally in fossil fuels. The burning of fossil fuels in power plants, vehicles, industrial units, power generators and residential heating systems, therefore releases significant amounts of sulphur dioxide. Sulphur dioxide is readily absorbed in the respiratory system. Being a powerful irritant, it aggravates the symptoms of people who suffer from asthma, bronchitis, emphysema, and other lung diseases. Sulphur dioxide also responsible for acid rain and haze.
1. What are pollutants?
2. List some effects of sulphur dioxide on human beings.
3. List some of the air pollutants.
The important oxides of nitrogen that cause air pollution are nitric oxide (NO) and nitrogen dioxide (NO₂). Collectively they are represented as NOx.
The biggest source of nitrogen oxides is the burning of fossil fuels in vehicles, power plants, industrial units, and generators used to produce electricity. Car engines produce a lot of nitrogen oxides. Oxides of nitrogen are highly toxic and are responsible for acid rain, photochemical smog, headache, and respiratory problems.
Carbon dioxide (CO₂) is a major air pollutant that has received increasing attention due to its association with climate change and global warming. Although it occurs naturally in the Earth's atmosphere, human activities such as burning fossil fuels, deforestation, and industrial processes have dramatically increased its levels.
Incomplete combustion occurs when there is not enough oxygen in the combustion process. It is a major source of carbon monoxide and particulate matter. It is mainly emitted by vehicles, industrial processes and residential heating systems that use fossil fuels and wood. Particulate matter refers to a mixture of fine particles suspended in the air, including soot, smoke, dust and other solid or liquid substances. These particles can have harmful effects on human health, especially if they penetrate deep into the lungs, causing respiratory problems and lung cancer.
Carbon monoxide is a toxic gas. When inhaled, it combines with hemoglobin to form carboxy hemoglobin, which is unable to carry oxygen causing you to lose consciousness and suffocate. It does not allow blood cells to absorb oxygen and can cause death. Carbon monoxide is a colourless and odourless gas, so its presence cannot be felt.
Methane enters the atmosphere from a variety of sources, including the decomposition of vegetation and waste. Wetlands, rice fields, landfills, and livestock are important sources of methane emissions. Methane is also produced during the digestive process in animals such as cows, goats, and sheep. These animals have a unique digestive system that produces large amounts of methane during digestion, which is released through belching and flatulence. Higher levels of methane contribute to the global warming, which is responsible for climate change.
Ground-level ozone is often called smog. It is a secondary pollutant produced by complex reactions between nitrogen oxides and volatile organic compounds (VOC) under the influence of sunlight. These reactions occur mainly in industrial and urban areas where emissions from industrial units and car engines are common. In sunlight, a series of chemical reactions occur between photochemical organic compounds and reactions. Sunlight breaks nitrogen dioxide into nitrogen monoxide and atomic oxygen.
Atomic oxygen (O) then reacts with oxygen molecules (O₂) to form ozone (O₃). This ozone can irritate the respiratory organs and cause asthma and other respiratory problems. It can also damage vegetation, reduce yield, and damage forests.
Write the names of main pollutants in the air.
Complete the following reactions.
a) SO₂(g) + O₂(g) →
b) C(s) + O₂(g) →
c) CO(g) + O₂(g) →