All questions of Air for JAMB Exam

Nitrogen

Argon in the Industry: Welding and Cutting Metals

Argon is an inert gas that is widely used in various industries for different purposes. One of its primary applications is in welding and cutting metals. Here's an explanation of why argon is used in this industry:

1. Inert Atmosphere:
- Argon is an inert gas, which means it does not react with other substances under normal conditions.
- When it is used in welding and cutting processes, argon creates an inert atmosphere that protects the metal from reacting with oxygen, nitrogen, and other gases in the air.
- This helps prevent the formation of oxide layers, which can weaken the weld or cut.

2. Shielding Gas:
- Argon is commonly used as a shielding gas in various welding techniques such as gas tungsten arc welding (GTAW) and gas metal arc welding (GMAW).
- In GTAW, also known as TIG (Tungsten Inert Gas) welding, argon is used as a shielding gas to protect the welding area from atmospheric contamination.
- Similarly, in GMAW, also known as MIG (Metal Inert Gas) welding, argon is used as a shielding gas to prevent oxidation and improve the quality of the weld.

3. Heat Transfer:
- Argon has excellent thermal conductivity, which means it can efficiently transfer heat away from the welding or cutting area.
- This helps to control the temperature of the metal and prevent overheating, which can lead to distortion or other defects in the weld.

4. Stable Arc:
- Argon produces a stable and smooth welding arc, which is essential for achieving precise and high-quality welds.
- The stable arc allows welders to have better control over the welding process, resulting in improved accuracy and reduced spatter.

5. Non-Flammable:
- Argon is non-flammable, making it a safe choice for welding and cutting operations.
- This characteristic ensures that the gas itself does not pose a fire hazard during the welding process.

In conclusion, argon is widely used in the industry for welding and cutting metals due to its inertness, shielding properties, heat transfer capabilities, stable arc formation, and non-flammability. These properties make argon an ideal gas for creating a controlled and protected environment during welding and cutting processes, resulting in high-quality and reliable metal joints and cuts.

Role of Carbon Dioxide in Photosynthesis
Photosynthesis is a vital process carried out by plants, algae, and some bacteria to produce food in the form of glucose. Carbon dioxide (CO2) plays a crucial role in this process as it is one of the key raw materials required for photosynthesis.

Key Points:
- During photosynthesis, plants take in carbon dioxide from the atmosphere through small openings called stomata present on their leaves.
- Inside the chloroplasts of plant cells, carbon dioxide combines with water in the presence of sunlight and chlorophyll to produce glucose and oxygen.
- The reaction can be summarized as: 6CO2 + 6H2O + light energy → C6H12O6 + 6O2.
- The glucose produced serves as food for the plant, while the oxygen is released back into the atmosphere as a byproduct.
- This process is essential for maintaining the balance of gases in the atmosphere and providing oxygen for animals and humans to breathe.
In conclusion, carbon dioxide is a critical gas in photosynthesis as it is used by plants to produce energy-rich glucose, which serves as food for the plant and oxygen for other organisms.

Understanding the Greenhouse Effect
The greenhouse effect is a natural process that warms the Earth’s surface. It occurs when the sun's energy reaches the Earth and is reflected back into space. Some of this energy is trapped by greenhouse gases in the atmosphere, which helps to maintain a temperature suitable for life.
Key Greenhouse Gases
Greenhouse gases include:
- Water vapor
- Carbon dioxide (CO2)
- Methane (CH4)
- Nitrous oxide (N2O)
While all these gases contribute to the greenhouse effect, carbon dioxide plays a particularly significant role.
Why Carbon Dioxide?
- Human Activities: Carbon dioxide is primarily released through human activities such as burning fossil fuels (coal, oil, and natural gas) and deforestation. These activities have drastically increased the concentration of CO2 in the atmosphere.
- Long Atmospheric Lifetime: CO2 remains in the atmosphere for a long time, which means it can trap heat over extended periods, contributing to global warming.
- Heat Absorption: Carbon dioxide effectively absorbs infrared radiation emitted by the Earth's surface. This absorption and re-emission of heat energy help to elevate global temperatures.
The Role of Other Gases
- Water Vapor: Although water vapor is the most abundant greenhouse gas, its levels are mainly controlled by natural processes. It amplifies the effects of other greenhouse gases but is not directly influenced by human activities.
- Comparative Impact: While nitrogen and oxygen are the primary components of the atmosphere, they do not contribute to the greenhouse effect as they do not absorb infrared radiation.
In conclusion, while several gases contribute to climate change, carbon dioxide is particularly critical due to its human-induced increase, long-lasting presence, and effective heat-trapping ability.

Argon in Trace Amounts in Air

Argon is the noble gas present in air in trace amounts. Here's an explanation breaking down this concept:

What are Noble Gases?
Noble gases are a group of elements found in the far right column of the periodic table. They are known for their stability due to having a full outer electron shell, making them unreactive.

Presence of Argon in Air
- While nitrogen and oxygen make up the majority of Earth's atmosphere, there are trace amounts of other gases present as well.
- One of these trace gases is argon, which accounts for about 0.93% of the Earth's atmosphere.
- Argon is produced through the radioactive decay of potassium-40 in the Earth's crust.

Properties of Argon
- Argon is colorless, odorless, and non-reactive.
- It is used in various applications such as welding, lighting, and in the production of semiconductor materials.

Importance of Argon
- Despite being present in small amounts in the atmosphere, argon plays a crucial role in maintaining atmospheric pressure and composition.
- It is also used in various industrial processes due to its inert nature.

In conclusion, while argon is only present in trace amounts in the air, its unique properties and applications make it an important element in various industries and in maintaining the stability of Earth's atmosphere.

Understanding Carbon Dioxide in the Atmosphere
Carbon dioxide (CO2) is a critical component of Earth's atmosphere, playing a significant role in the greenhouse effect and supporting life through photosynthesis.
Approximate Percentage of Carbon Dioxide
- The concentration of carbon dioxide in the atmosphere is approximately 0.04%.
- This translates to about 400 parts per million (ppm).
Comparison with Other Gases
- Oxygen (21%): The second most abundant gas in the atmosphere, essential for respiration in most living organisms.
- Nitrogen (78%): The most abundant gas, making up a large majority of the atmosphere, but it is inert and does not support life directly.
- Other Gases (Less than 1%): This includes argon, neon, helium, and trace gases like ozone and methane.
The Role of Carbon Dioxide
- Photosynthesis: Plants absorb CO2 to produce oxygen and glucose, fundamental for life on Earth.
- Greenhouse Effect: CO2 traps heat in the atmosphere, helping to regulate Earth’s temperature.
Environmental Impact
- Climate Change: Increased levels of CO2 from human activities, like burning fossil fuels, contribute to global warming and climate change.
Conclusion
Understanding the composition of air, particularly the small but vital percentage of carbon dioxide, is crucial for grasping environmental science and the impacts of human activities on our planet.