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Lesson 09 – What Is So Great About Gases?

Read About Gases


Can you find where all the definitions are in the text?

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What Is So Great About Gases?

Lots of inventions that people use every day rely on gases.

Air Bags in Cars

Airbags save lives and prevent injuries. An airbag inflates when it is filled with nitrogen gas.
How does an airbag work? A car contains a crash sensor that can detect when a crash has taken place. The crash sensor sends a signal to the air bag’s inflator. In the inflator, two chemicals react with each other in a chemical change that produces nitrogen gas. As the nitrogen gas starts to fill the airbag, the bag pops out and fully inflates. Tiny holes in the airbag allow the gas to escape so the passenger is not trapped behind the airbag.

An airbag has to inflate at lightning speed if it is going to prevent injury. Airbags burst out of their storage site at a speed of over 300 km/h. From the time a crash sensor detects a crash to when the airbag is fully inflated is only 1/25 of a second!

Aerosol Cans

Room fresheners and hairspray are available in aerosol cans, sometimes called spray cans. Gas is what makes aerosol cans work.

An aerosol can have gas at the top and the product (such as hairspray) at the bottom. The gas pushes down on the product. Since the product has nowhere to go, nothing happens. When you press the nozzle, you create an opening so the product has somewhere to go. The pushing force of the gas makes the product rush up a plastic tube. The product comes out of the nozzle in a spray.

The gas used in some aerosol cans is harmful to the environment. Many people choose products in a pump container instead.

Fire Extinguishers

Most fire extinguishers use a chemical foam or powder to put out fires. One type of extinguisher uses gas to put out fires. The tank of this extinguisher is filled with liquid carbon dioxide. When the extinguisher is activated, the liquid carbon dioxide changes to a gas as it sprays out.

Fire needs oxygen. A fire will go out if not enough oxygen is available. Carbon dioxide gas pushes the oxygen away. The fire goes out because there is not enough oxygen around the fire to keep it burning.

Now Show What You Know!

Complete some questions about the reading selection by clicking “Begin Questions” below.