Monday, March 29, 2010

Weigh Some Air

Weigh Some Air p.8
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 as 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 are:
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, andash; 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.

Mini Lesson Plan
Title: Weigh some air
Grade Level: Fourth grade
Learning Outcomes:
1.) Students will predict the result of placing one air-filled balloon on one side of the balance and an empty balloon on the other side of the balance.
2.) Students will analyze the materials present in air that help give it weight.
3.) Students will construct an experiment.
4.) Students will understand that air is not light and takes up space.
Science Standards:
GLE 0407.Inq.2 Select and use appropriate tools and simple equipment to conduct an investigation.
GLE 0407.9.1 Collect data to illustrate that the physical properties of matter can be described with tools that measure weight, mass, length, and volume.
GLE 0407.9.2 Explore different types of physical changes in matter.

Materials Needed:
Balloons, stick, tape, air pump, rubber band, two tacks, pencil, long piece of pen, ruler, thread

Activity:
1.) Have a class discussion about air. Have them predict if they think air is light.
2.) Group the students into groups of four.
3.) Give each group of students all the materials needed for the experiment.
4.) Have students follow the procedures on the worksheet provided for them.
5.) After each group has completed the experiment, have the students discuss their predictions.

Assessment:
The teacher can assess students by observing the groups throughout their experiment and by their finished product.

Additional Links:
Air Weight

Crush Some Air

4 comments:

  1. Great job! You did a good job explaining the concept and the mini lesson is great also. It would be fun for students to try adding balloons to each side of the ruler to balance the weight.

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  2. Great presentation! This was an interesting experiment to show that air has mass and takes up space. Good job!

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  3. Great job girls! Very neat experiment. Great background information.

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  4. Great experiment! Could you maybe link this experiment to the one that Erin & I did on crush with air, where you crush a pop bottle with air. You could do your experiment first to show that air does have weight and then show that it can crush the bottle.

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