Properties of air

you will see properties of air

1. Properties of air

2. Properties of air Air is an example of matter. Air is a mixture of gases consisting of approximately 4/5 Nitrogen and 1/5 Oxygen. Like all matter, air has weight and takes up space. It can also be compressed, unlike solids and liquids. These three properties will be studied in this investigation. Air has weight--Weighing Air Air takes up space--The Upside-Down Cup Air can be compressed--The Cartesian Diver Air  Takes Up Space

3. Air Exerts Pressure Take a meter stick and lay it on a table. Unfold a full page of a newspaper and lay it flat over the meter stick. Push down on the other end of the meter stick. What happens? Why can’t you lift a super-light piece of paper?  Air exerts pressure (in all directions ). The air above the paper pushes down on it (pressure). This pressure is what makes the paper lay flat on the table - it’s being pushed down. Even though they’re too tiny to see, all the molecules of air in the atmosphere above your head weigh something. And the combined weight of these molecules causes a pressure pressing down on your body of 10,000 kg per square meter (10,000 kg = 22,000 lbs). This means that the mass of the air above the 0.1 square meter cross section of your body is 1,000 kg, or a tone.

4. Air is affected by Temperature Take a balloon and place it over the top of a pop bottle (2L is best with a little bit of water in it). Observe the size of the balloon now (@room temperature). Now place it in a freezer for 10 minutes, remove it and observe size of balloon. Now take the bottle and hold it in a baking dish of almost-boiling water for 10 minutes. Now let the bottle sit on the table for 10 minutes. You should now see the balloon return to the same size as it was to start.

5. Air is affected by Temperature The greater the temperature, the faster the air particles move (increasing pressure), hitting the sides of the balloon more often and harder, making the balloon inflate more. The colder the air becomes though, the slower the air particles move (lowering pressure), resulting in the same amount of air now taking up less space. This is why the beach-ball you left in the garage over night will be “smaller” in the morning that it was during the day (when it was warmer)

6. Air has weight Air has weight. Matter has three forms which are solid, liquid and gas. Air is a mixture of gases so it will have weight. We can demonstrate that air has weight by comparing a full balloon with an empty balloon

7. Air takes up space The Upside-Down Cup demonstrates that air takes up space. Students are challenged to devise a way to submerge a tissue in water in such a way as it does not get wet. The solution is to stuff the tissue into the bottom of a cup which is then held in the water upside-down.

8. Air Takes Up Space Take an empty Ziploc bag, open it and pull it through the air like a parachute. Now close it, seal it and try to squish the bag. There’s nothing in the bag, right? Wrong. The ziploc bag is full of air.  You can also prove this by blowing up a balloon. The balloon expands because you are putting something into the balloon; air. This air takes up space, so the more air you put into the balloon, the more space it takes up. When you use a pump to blow up a football, you don’t put nothing into it, you put air into it - this air takes up space which is why the football expands.

9. Air can be compressed The Cartesian Diver demonstrates that air can be compressed. It is generally credited to Rene Descartes, the French mathematician and scientist who also developed the Cartesian Coordinate System which we use for making graphs.

10. Despite this “pretend” atmosphere, the air pressure inside an plane is not the same as at sea level. You might have noticed that if you drink from a plastic bottle during a flight and put the lid back on, when you land the bottle will be crushed. This is because the air in the bottle is at the lower pressure of the airplane cabin and it can’t withstand the higher air pressure at ground level.  Air is affected by Altitude

11. Air is affected by Altitude The higher you are, the lower the air pressure. There is less air above you to push the air down (which would increase the air pressure). This is why climbers on Everest use oxygen tanks - the air outside is too thin at the summit for them to breathe normally. Human bodies are used to air pressure. The air pressure in our lungs, ears and stomachs is the same as the air pressure outside of our bodies, which ensures that we don’t get crushed. Our bodies are also flexible enough to cope when the inside and outside pressures aren’t exactly the same. Airplanes need pressurized cabins to compensate for the lower air pressure at high altitudes