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What is a gas? A gas is a state of matter in which the molecules are widely separated, move around freely, and move at high speeds. The main gases that make up air are: nitrogen, carbon dioxide and oxygen.

Can we see air or a gas? Not by itself. We can see air bubbles in a fish tank or bubbles clinging to the side of a soda bottle. We can feel a warm breeze or a blast of cold air from an air conditioner or on a winter day when we go outside. We can see our breath (water vapor) on a cold day, steam rising from a boiling pot on the stove or feel our breath when we exhale. We can see the trees and leaves blowing in the wind. We can feel the effects of changing air pressure on a plane as it ascends and descends, and sometimes even on an elevator in a very tall building when we go up to a high floor.


How To Develop Your Gas Science Story

Use the inquiry-based content development process to develop content. In the process of asking questions and filling-in the blanks you will develop your science story.

What is a gas? A gas is one of the states of matter. Air is a gas. It is made up of many gases. One of those gases is oxygen. Oxygen is what we breathe. We inhale oxygen and exhale carbon dioxide.

What are the other states of matter? The states of matter are solids, liquids, gases and plasma. All naturally occurring elements on Earth can exist as either as solid, liquid or a gas, depending on the temperature and pressure. (Think about water and its various states.)

Why are gases important? Gases take up space. They make up the atmosphere. Gases exert pressure.

What if there were no gases? There would be nothing for us to breathe. Water would not be recycled from its solid and liquid states since there would be no evaporation. Note: Show, don't just tell. Use your gas exploration to demonstrate that water in a puddle or a glass will evaporate over time. Where does it go? Up into the air. It becomes a gas.


Are all gases the same? Compare a helium-filled balloon to an air-filled balloon. Both contain gases, but helium is lighter than air. It takes up less space than air. Helium is less dense than air.

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About Gases...

While most common gases cannot be seen under natural conditions we can feel the effects of gases and demonstrate certain properties. The following series of experiments and activities are designed to demonstrate the "existence" of gases as a physical phenomenon. The experiments also progress the science story, providing numerous familiar examples of gases and where we "find" them.

how2GASES Experiments



Smoke Rises-Warm Air Rises

Most children have or will be taught the basics about what to do in case of a fire-stay low to the floor because there is less smoke near the floor. But why? Warm air, air that has been heated by fire is less dense than cooler air. Smoke rises. It's hotter. The cleaner air is in fact closer to the floor.

Explore Wind or Air Power.

As you explore gases make available a variety of air or wind-powered objects of interest, such as, wind chimes, an air pump and bicycle tire, wind instruments, pinwheels, or race a few handmade sailboats across your sensory table.


Context & Connections: Fizzy Stuff

At some point you have likely combined baking soda and vinegar, or dropped an Alka-Seltzer tablet into water to make a "volcano" reaction with your class. You can utilize a variation on this experiment to specifically show the production of a gas, in this case carbon dioxide.

Prepare your reaction using either baking soda/vinegar or Alka-Seltzer. For the former, add one-quarter cup of vinegar to a plastic, 1 liter water bottle. Load a tablespoon of baking soda into a 9" balloon then carefully place it over the bottle's opening, allowing the balloon to sag to prevent the baking soda from falling into the bottle. When you are ready to start the reaction, lift the drooping portion of the balloon to allow the baking soda to fall into the bottle. A significant amount of carbon dioxide is formed and the balloon will inflate quickly. NOTES:If you decide to perform this experiment, be aware that occassionally the balloon will pop. If you become uncomfortable, move the bottle away from your class and remove the balloon over a sink. If you decide to use Alka-Seltzer be sure to break the tablet into small chunks to keep the reaction in check.

Before & After. In addition to the volcano-type reaction described above, there are other ways of showing how gases function and their properties. Gases are less dense than liquids. In other words, gases are lighter than water. Carbonated soda is a classic example of tiny bubbles. You can experiment with a warm bottle of soda, or drop a few ice cubes into a clear cup filled with warm soda. The bubbles in all three instances will ultimately rise to the top. What happens to those bubbles? They pop and the gas is released. You can also add a handful of raisins to a clear cup filled with soda. The carbon dioxide bubbles will cling to the raisins, eventually causing them to rise in the cup. When the bubble-laden raisins reach the surface of the liquid, the bubbles pop and the raisins sink.

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