Grade 9
  1. Matter and its nature  1.1. Introduction to matter  1.2. Physical and chemical properties of matter  1.3. States of matter  1.3.1. Solid state  1.3.2. Fluid state  1.3.3. Gaseous state  1.3.4. Plasma and Bose–Einstein condensate  1.4. Changes in the states of matter  1.4.1. Melting and freezing  1.4.2. Evaporation and Condensation  1.4.3. Sublimation and deposition  1.5. Classification of matter  1.6. Elements, Compounds, and Mixtures  1.7. Pure substances and impurities  1.8. Separation Techniques  1.8.1. Filtration  1.8.2. Distillation  1.8.3. Crystallization  1.8.4. Chromatography  1.8.5. Centrifugation  1.8.6. Sublimation  1.8.7. Decantation and sedimentation
  2. Atomic Structure  2.1. Discovery of atoms  2.2. Dalton's atomic theory  2.3. Structure of the atom  2.4. Subatomic particles  2.5. Atomic number and mass number  2.6. Isotopes and Isobars  2.7. Electronic configuration  2.8. Bohr's atomic model  2.9. Modern Atomic Model (Quantum Mechanical Model - Introduction)  2.10. Valency and chemical bonding
  3. C hemical reactions and equations  3.1. Introduction to Chemical Reactions  3.2. Chemical Equation Formulation  3.3. Balancing Chemical Equations  3.4. Types of Chemical Reactions  3.4.1. Combination Reactions  3.4.2. Decomposition reactions  3.4.3. Displacement reactions  3.4.4. Double displacement reactions  3.4.5. Redox reactions  3.4.6. Endothermic and Exothermic Reactions  3.5. Effects of chemical reactions  3.6. Energy Changes in Chemical Reactions  3.7. Catalysts and their role in reactions
  4. Periodic table and periodicity  4.1. History of Periodic Classification  4.2. Mendeleev's periodic table  4.3. Modern Periodic Table  4.4. Periods and groups in the periodic table and periodicity  4.5. Trends in the Periodic Table  4.5.1. Atomic size  4.5.2. Ionization Energy  4.5.3. Electron affinity  4.5.4. Electronegativity  4.5.5. Metallic and Non-Metallic Properties  4.6. Noble gases and their properties
  5. Chemical bond  5.1. Introduction to Chemical Bonding  5.2. Types of chemical bonds  5.2.1. Ionic bond  5.2.2. Covalent bond  5.2.3. Metallic bond  5.2.4. Hydrogen bonding  5.2.5. Van der Waals force  5.3. Properties of Ionic and Covalent Compounds  5.4. Molecular Structure and Geometry (VSEPR Theory - Basics)
  6. Acids, Bases and Salts  6.1. Introduction to Acids and Bases  6.2. Properties of Acids  6.3. Properties of bases  6.4. pH scale and its importance  6.5. Indicators and their uses  6.6. Neutralization reactions  6.7. Strength of Acids and Bases (Strong vs. Weak)  6.8. Preparation of salts  6.9. Uses of acids, bases and salts in daily life
  7. Metals and Nonmetals  7.1. Physical Properties of Metals  7.2. Physical Properties of Nonmetals  7.3. Chemical properties of metals  7.4. Chemical Properties of Nonmetals  7.5. Reactivity Series of Metals  7.6. Extraction of metals  7.7. Corrosion and its prevention  7.8. uses of metals and nonmetals
  8. Carbon and its compounds  8.1. Introduction to Carbon  8.2. Allotropes of carbon (diamond, graphite, fullerene)  8.3. Hydrocarbons  8.3.1. Hydrocarbons  8.3.2. Alkene  8.3.3. Alkynes  8.4. Functional groups in organic chemistry  8.5. Isomerism in organic compounds  8.6. Alcohols and Carboxylic Acids  8.7. Soaps and detergents  8.8. Polymers (Introduction to Natural and Synthetic Polymers)
  9. Solutions and Mixtures  9.1. Types of mixtures  9.2. Homogeneous and Heterogeneous Mixtures  9.3. Concentration of solutions  9.4. Solubility and factors affecting solubility  9.5. Suspensions and Colloids  9.6. Saturated, unsaturated and supersaturated solutions
  10. Air and atmosphere  10.1. Composition of air  10.2. Role of gases in the atmosphere  10.4. Acid rain and its effects  10.5. Greenhouse effect and global warming  10.6. Ozone layer and its depletion  10.7. Air pollution control measures
  11. Water and its importance  11.1. Composition and properties of water  11.2. Hardness of water (temporary and permanent hardness)  11.3. Causes of water pollution  11.4. Effects of Water Pollution  11.5. Water purification methods (filtration, boiling, chlorination)
  12. Industrial Chemistry  12.1. Introduction to Industrial Chemistry  12.2. Important industrial chemicals (sulfuric acid, ammonia, sodium hydroxide)  12.3. Chemical processes in industry  12.4. Uses of Industrial Chemistry in Daily Life  12.5. Environmental impact of industrial chemical processes

Grade 9 → Air and atmosphere ↓


Composition of air


Introduction

Air is a fascinating and vital component of our planet, making life possible. It is an invisible mixture of gases that surrounds the Earth, commonly called the Earth's atmosphere. Understanding its composition is fundamental to understanding many aspects of chemistry and environmental science.

Major components of air

The main components of air include nitrogen, oxygen, argon, carbon dioxide, and trace amounts of other gases. Let's break down these components:

Nitrogen (N2)

Nitrogen is the most abundant gas in the air, making up about 78% of the atmosphere. Nitrogen gas is chemically inert, meaning it does not easily react with other substances. It plays an important role in the biological nitrogen cycle.

N2 + 3H2 → 2NH3

This chemical equation shows the production of ammonia (NH3) using nitrogen, an important process in agricultural fertilizer manufacturing.

78% Nitrogen

Oxygen (O2)

Oxygen is the second most abundant gas, making up about 21% of the air. It is vital to survival as it is used in the respiratory and combustion processes of most organisms.

C + O2 → CO2

This equation burns carbon (C) to produce carbon dioxide (CO2), which is an essential part of energy production.

21% Oxygen

Argon (Ar)

Argon makes up about 0.93% of the air. It is a noble gas, meaning it is inert under most conditions. Although it is not directly important for biological processes, it is used in a variety of industrial applications where an inert atmosphere is required, such as in arc welding.

Carbon dioxide (CO2)

Carbon dioxide is a trace gas, making up about 0.04% of the atmosphere. Despite its low concentration, it has a significant effect on the Earth's climate, as it is a major greenhouse gas.

CO2 + H2O → H2CO3

This equation shows how carbon dioxide dissolves in water to form carbonic acid, a process vital to Earth's carbon cycle.

0.04% CO2

Minor components of air

Although they are present in very small quantities, trace gases and particles have a big effect. These include neon, helium, methane, krypton, hydrogen, ozone, and water vapor.

Neon (Ne), Helium (He), Krypton (Kr)

These are inert gases present in very small quantities. They are mostly used in lighting and as protective gases in high-temperature industrial processes. For example, neon is famous for its use in colorful neon signs.

Methane (CH4)

Methane is another important greenhouse gas, although it is present in smaller quantities than CO2. It is produced by biological activity in anaerobic environments such as swamps and is a major component of natural gas.

CH4 + 2O2 → CO2 + 2H2O

This equation shows the combustion of methane produces carbon dioxide and water, which is why it is such a valuable fuel.

Ozone (O3)

Ozone is present in trace amounts in the Earth's stratosphere and plays a vital role in protecting life by absorbing the Sun's harmful ultraviolet radiation.

Water vapor (H2O)

Water vapor varies greatly depending on location and climatic conditions. In dry atmospheres, it comprises about 1% of the air, but in humid tropical regions, it can be as high as 4%. Water vapor is an important greenhouse gas and plays an important role in weather patterns and the water cycle.

Importance of trace gases

Although these gases are present in small quantities, they are essential for various processes on Earth. They contribute to the greenhouse effect, help absorb radiation, and play an important role in chemical interactions in the atmosphere.

Variability of air composition

The composition of air can vary slightly depending on a number of factors such as altitude, pollution and geographic location. For example, urban areas have higher concentrations of carbon monoxide and sulfur dioxide due to human activities.

Conclusion

Understanding the composition of air is essential to understanding Earth's environmental and biological processes. It also underscores the delicate balance needed to sustain life and the important role that trace gases play in this balance. Recognizing this composition helps us understand the complexity of Earth's atmosphere and the need to preserve it.

Air is an incredible natural resource that supports life on Earth in ways we continue to discover and appreciate. By studying its composition, we not only learn more about our life-sustaining planet but also understand how we can preserve it for future generations.


Grade 9 → 10.1


U
username
0%
completed in Grade 9

← Prev (10)
Air and atmosphere
Next (10.2) →
Role of gases in the atmosphere

Comments 



Composition of air

https://www.chemistryelite.com/g9/10.1?ceal=en