Air's Chemical Composition & Environmental Effects

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  • 0:01 Smells in the Air
  • 0:43 What Is in Air?
  • 2:57 Defining Air Pollution
  • 3:40 Air Pollution Wars
  • 6:07 Lesson Summary
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Lesson Transcript
Instructor: Nicola McDougal

Nicky has taught a variety of chemistry courses at college level. Nicky has a PhD in Physical Chemistry.

Air is all around us. We breathe in air every second, of every day. We couldn't survive without it. In this lesson, we will learn about the chemicals that make up air. We will look at sources of air pollution, the effect it has on us, and the environment we live in.

Smells in the Air!

Imagine you are in your bedroom playing video games and suddenly you smell the enticing aroma of freshly baked cookies. Mmm, that smell is so yummy; it immediately sends you running to grab one.

Now imagine you are skateboarding in the park and you smell something burning. You look around and see a big pile of wood on fire. This time you run away from the smell and call the fire service.

In each case, your nose is telling you something very important. It is telling you that there is a specific chemical in the air, and your brain reacts to it. This lesson is all about chemicals in air, both the good ones and the bad ones!

What Is in Air?

Take a gulp of fresh air! Feels good, doesn't it? We all breathe gallons of air every day. We hope the air is mainly clean and fresh. But this is not always the case, and air can become polluted.

But before we look at pollution, let us first look at the different gases that make up air. Air is a mixture of gases. This means two or more pure substances hang out together in variable amounts but do not chemically combine together. There are two main gases in air. Nitrogen is the largest component in air, at about 79%. Nitrogen is colorless and odorless. It doesn't react much in our body, and so we breathe pretty much all of it back out.

Oxygen is the second main gas in air, at around 20%. It is vital for our survival. Oxygen is absorbed into our blood through our lungs, and it allows respiration to occur. Respiration is the process of producing energy in living organisms. Oxygen is needed to react with the food we eat to release the energy we need. Carbon dioxide is the main product of respiration, and we breathe this out.

The final one percent of air is made up of other gases. Argon is the third main gas in the air, at about 0.9%. Carbon dioxide is also present in tiny amounts.

Unfortunately, there is no such thing as completely pure air. Both human activities and natural events add different chemicals to the air. Because air is a mixture, the other gases just move aside to let the new ones join them. This is just like when you are at a party. There is always room for a few more people to join in.

Examples of new chemicals added to the air are the chemicals given off by your freshly baked cookies and the burning fire at the beginning of the lesson. Of course, not everything new in the air is harmful; yummy cookie smell isn't. But many other things are, and these are known as air pollutants.

Defining Air Pollution

So, what do we mean by air pollution? Air pollution is the presence in air of a substance that has harmful or poisonous effects. Even in very tiny amounts, some air pollutants are harmful and could even kill us.

Air pollution is nothing new. London had real problems with air pollution years ago. A massive smog, which is a mix of smoke, fog, and pollutants, engulfed the city in the 1950s, and many thousands died as a direct result of breathing in the polluted air. This pollution was caused by burning coal. Unfortunately, smog is still a big problem in many cities today.

So, what causes all this air pollution? Let us look at two main offenders.

Air Pollution Wars

Welcome to air pollution wars. In the red corner, we have you and the planet Earth. And, in the blue corner, we have the innocent-looking car and a coal-fired power plant. Let the battles commence!

Battle one, the car. What a beast this is! Car exhaust is responsible for a number of important air pollutants, including ozone, carbon monoxide, and nitrogen dioxide.

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