Question

What is Earth's atmosphere composed of? Why would you die of suffocation if you were to parachute from an airplane at an elevation of \(12 \mathrm{~km}\) without taking an oxygen tank with you?

Short answer

Earth's atmosphere is composed mainly of nitrogen (78%) and oxygen (21%), with small amounts of other gases such as argon, carbon dioxide, and trace gases. A person would die of suffocation at an elevation of 12 km without an oxygen tank because the air pressure and oxygen concentration are significantly lower at that altitude. The reduced oxygen concentration (around 10%) is not sufficient for proper human respiration, leading to hypoxia, suffocation, and potentially death.

Step-by-step solution

Part 1: Composition of Earth's atmosphere

Earth's atmosphere is made up of several gases, with the most abundant being nitrogen and oxygen. The other gases include water vapor, argon, carbon dioxide, and trace amounts of neon, helium, methane, krypton, and xenon. The approximate percentages of these gases are: - Nitrogen: 78% - Oxygen: 21% - Argon: 0.93% - Carbon dioxide: 0.04% - Trace amounts of other gases: 0.03% Of these gases, oxygen is the most essential for human survival, as it's required for cellular respiration.

Part 2: The reason for suffocation at 12 km elevation without an oxygen tank

The reason why a person would die of suffocation if they were to parachute from an airplane at 12 km elevation without an oxygen tank is due to the fact that air pressure decreases with altitude, and so does the concentration of oxygen in the atmosphere. At 12 km elevation, the air pressure is considerably lower than at sea level. The oxygen concentration in the atmosphere at this altitude is around 10%. This value is insufficient to sustain proper human respiration and, as a result, a person would experience a lack of oxygen (known as hypoxia), which can lead to suffocation and death if he or she does not take an oxygen tank with them. In summary, the Earth's atmosphere is composed mainly of nitrogen and oxygen, with the latter being essential for human survival. At an elevation of 12 km, the concentration of oxygen in the atmosphere is insufficient for proper respiration. Thus, a person would die of suffocation without an oxygen tank in these conditions.

Key concepts

Oxygen in Atmosphere

Oxygen is a key component of Earth's atmosphere and is vital for all aerobic life forms, including humans. It makes up about 21% of the atmosphere, providing the necessary supply to sustain both plant and animal life.
Despite being only a fifth of the atmosphere's composition, oxygen's role is crucial in supporting the process of cellular respiration. This process is how our cells obtain energy from food, using oxygen to convert glucose into usable energy.
Besides oxygen, the atmosphere consists significantly of nitrogen, around 78%, which is largely inert but serves purposes like nutrient supply for plants. Argon, carbon dioxide, and other trace gases fill out the remaining portion, each playing specific roles in atmospheric processes and life support, from preserving heat to supporting photosynthesis.

Air Pressure and Altitude

Air pressure acts as a vital force in our daily lives by affecting the availability of oxygen. At higher altitudes, such as 12 km above sea level, air pressure decreases significantly. This reduction in pressure also leads to a decrease in the amount of oxygen available.
To visualize this, imagine sitting inside a closed container. At sea level, the container is full of air molecules squished tightly together by the weight of the air above. As you travel higher, the air above lessens, causing fewer air molecules, and thus less oxygen, in the same container.

• At sea level, air is denser with plenty of oxygen for every breath.
• Higher altitudes mean 'thinner' air with less oxygen for the lungs to absorb, which can lead to breathing difficulties and hypoxia.

Understanding this concept is key to why supplemental oxygen becomes necessary at altitudes reached by aircraft.

Human Respiration and Oxygen Levels

Human respiration is intricately linked to the levels of oxygen in the atmosphere. Our bodies are finely tuned to breathe the mixture of gases found at sea level. But as we go higher, the reduced oxygen availability can challenge our respiratory systems.
The body relies on oxygen to produce energy. With less oxygen at high altitudes, the body struggles to function normally, which can cause symptoms like dizziness, fatigue, and headaches – early signs of hypoxia.

• Without sufficient oxygen, the brain and organs can suffer damage.
• At extreme altitudes (such as 12 km), oxygen levels are too low to sustain human life, hence the risk of suffocation and the need for oxygen tanks.

The body's need for oxygen remains constant, so in scenarios where atmospheric oxygen is low, supplemental oxygen is vital to keep us safe and breathing comfortably.