Weigh Some Air

Weigh Some Air

(pg. 8 in experiment book)

People often use the expression "Its light as air". But the question is... Is air really light?

Background Information

Air is not empty space. It is made of matter - mainly different types of gases. The normal composition of air is about 78% nitrogen (N2), 21% oxygen (O2), and 1% other gases such argon (Ar), carbon dioxide (CO2), methane (CH4), and helium (He). Many gases are composed of molecules that are made up of atoms, the fundamental units of matter. Some gases are just made up of atoms. Air is essentially a layer surrounding the Earth made of of trillions and trillions of gas molecules.
Air also contains solid particles (e.g., dust, ash, etc.), water droplets, and ice crystals. These materials are also comprised of molecules that are made up of atoms. However, these materials are not considered part of the normal composition of air. Nevertheless, collectively, air is made up of matter such as gases, solid particles, water droplets, and ice crystals. All matter occupies space and has weight.

Purpose

To demonstrate that air has weight. The lesson is important for building a foundation regarding matter and its fundamental units, air and its properties, and air pollution concepts. The lesson also helps students begin developing observation and prediction skills.

Materials needed:
Balloon pump, Two tacks, Two balloons, Rubber band, Long thin piece of wood, Ruler, Pencil, Tape, Thread

1.) Use the ruler to find the center of the wood and then mark it.
2.) Push a tack into each side of the center mark.


3.) Tie the thread to the middle of the rubber band.

4.) Fix the loops of the rubber band around the tacks. Lift the wood by the thread. It should
balance.

5.) Tape one of the balloons to one end of the wood.


6.) Tape the second balloon to the other end of the wood. Check that it still balances. Then remove one balloon and blow it up.
(Look.. It still balances)


7.) Pump air into the balloon before placing it onto the stick.
Predict whether the inflated balloon will be heavier, stay the same, or be lighter than the deflated balloon.


8.) Tie the blown-up balloon and attach it to the wood in the same place using tape. The balloon makes the wood lose its balance.
Was your prediction accurate?
(When the balloon has been inflated, it becomes heavier because it contains air.)

Follow Up

Explain that the balloons and balance demonstrated that air has weight (and occupies space)because the side of the balance with the more air-filled balloon dropped lower than the side with the more empty balloon. Explain that air is not empty space, but is made of gases such as nitrogen,oxygen, argon, carbon dioxide, methane, and helium; solid particles such as dust, smoke, and ash; water droplets; ice crystals; and many other materials. These materials, or matter, are composed of very small units called atoms. All matter occupies space and has weight.

For a preview of our Mini Lesson Plan please click on the link

Source: Air Weight

Connected Link:

Crush Some Air