Introduction
Relevance of the Theme
We may not see it, but we live immersed in an invisible mixture of gases known as air. The importance of the theme 'Air Composition' is established in the critical need to understand what we breathe in our daily lives and how it impacts our health, as well as how our activities modify the composition of this air. By understanding the composition of the air, it becomes possible to discuss important environmental issues, such as air pollution and climate change.
The subject is fundamental for the science discipline, as it allows students a first glimpse into the principles of chemistry and the physical phenomena of the atmosphere. It is a way to connect scientific knowledge with everyday experience, contributing to the development of critical and scientific thinking.
Contextualization
In the science curriculum, the theme 'Air Composition' is usually addressed in the chemistry unit, more specifically when dealing with mixtures and pure substances. It is an introductory theme for more advanced concepts, such as chemical reactions and biogeochemical cycles.
It is inserted in the broader context of the discipline as a bridge between biology and chemistry - the respiration of living beings, the photosynthesis of plants, climate change, all have air as a common element. Therefore, the proper understanding of air composition is a fundamental foundation for the construction of scientific knowledge in basic education.
By exploring the composition of the air, we also establish connections with other areas of knowledge, such as geography (studying the climate), history (understanding the impact of industrial revolutions on the atmosphere), and health (discussing the relationship between air quality and respiratory diseases).
Theoretical Development
Components of Air
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Air is a homogeneous mixture of gases, which means that the various components that make up the air are evenly distributed. The mixture is so perfect that we cannot distinguish the different gases just by using our senses.
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Nitrogen (N2): The most abundant gas in the air we breathe, constituting approximately 78% of the total volume. Although essential for life, nitrogen is not directly used by the human body. However, it is fundamental for plants, which use it in the production of proteins.
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Oxygen (O2): The second most abundant gas in the air, representing about 21% of the total volume. Oxygen is vital for the respiration of almost all organisms and for the combustion of fire.
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Carbon Dioxide (CO2): Present in small quantities, about 0.04% of the total volume, but is extremely important for life on Earth. It is the gas used by plants in the process of photosynthesis to produce oxygen.
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Other gases: The rest of the air is composed of a variety of other gases in small quantities, such as argon, neon, helium, methane, among others.
Key Terms
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Atmosphere: Layer of air that surrounds the Earth, composed of a mixture of gases that keep it warm and protected from solar radiation.
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Homogeneous Mixture: It is a mixture in which the components are uniformly distributed, forming a single phase. The air mixture is a classic example of a homogeneous mixture.
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Photosynthesis: Process by which plants, algae, and some bacteria absorb energy from sunlight, CO2, and water to produce glucose (a sugar) and oxygen.
Examples and Cases
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Production and consumption of O2: While animals breathe oxygen and release carbon dioxide, plants 'breathe' carbon dioxide, releasing oxygen into the environment during photosynthesis. This balance is essential for the maintenance of life as we know it today.
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Global Warming: The increase in the concentration of gases, such as CO2 in the atmosphere, contributes to the greenhouse effect and consequent global warming. The excessive production of these gases is a result of human activities, such as the burning of fossil fuels.
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Air Pollution: The introduction of harmful substances or excess of natural substances into the air results in air pollution. This includes toxic gases released by industry or cars, cigarette smoke, and even natural dust that becomes concentrated at harmful levels. Air pollution can lead to health problems such as asthma, lung cancer, and heart diseases.
Detailed Summary
Relevant Points
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Importance of Nitrogen: Despite composing about 78% of the air, nitrogen is not directly used by the human body. However, this element is vital for plants, which need it for the production of proteins, and consequently, for our nutrition;
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Vital Function of Oxygen: Representing approximately 21% of the air, oxygen is fundamental for life. Besides being the gas we breathe, oxygen plays a crucial role in combustion reactions;
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Carbon Dioxide and Photosynthesis: Despite its low presence in the atmosphere (around 0.04%), carbon dioxide is essential for the photosynthesis process of plants, which by transforming CO2 into oxygen, ensure the maintenance of terrestrial life;
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Other Gases and Pollution: The atmosphere also has a series of other gases in small quantities, but which are of enormous relevance, especially when considering atmospheric pollution. Among them, we highlight Argon, Neon, Helium, and Methane;
Conclusions
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Interdependence in the atmosphere: Living beings and the atmosphere have a relationship of interdependence. Organisms consume and produce gases that make up the atmosphere, while changes in the composition of atmospheric gases can influence life on Earth;
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Pollution and Climate Change: Human activities such as industry and the burning of fossil fuels have altered the natural composition of the air. The increase in gases like carbon dioxide in the atmosphere contributes to the greenhouse effect and global warming;
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Health and Air Quality: The quality of the air we breathe is directly linked to our health. The excessive presence of harmful substances, resulting from pollution, can lead to respiratory and cardiovascular diseases.
Suggested Exercises
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Exercise 1: Discuss the role of nitrogen in the life cycle, considering its presence in the atmosphere and its importance for the nutrition of plants.
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Exercise 2: Explain why oxygen is essential for life and how its presence in the atmosphere influences phenomena such as combustion.
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Exercise 3: Analyze the relationship between greenhouse gases, global warming, and air pollution. How are these aspects interconnected and what is the influence of human activities on these processes.
