How to prove air has weight experiment

What does air weigh? - experiment and explanation

What does air actually weigh? That must be incredibly little, maybe it has no weight at all? This experiment gives a clue.

What you need:

  • two equal balloons
  • a long stick
  • some duct tape
  • two equal cans (or other blocks)
  • a flat-sided pencil

Does air have any weight at all?

As strange as it sounds, it wasn't until the 17th century that science became interested in air as a substantial "something", as opposed to a vacuum, which caused headaches and raised the question of whether it even existed.

  • Today we know that everything made of atoms and / or molecules also has weight. In the case of solids and liquids, this is also clear, as they can simply be placed on a scale and weighed.
  • But a gas like air? Pure air is colorless and you can neither taste nor smell it, and if you run your hand through the air, you actually feel absolutely nothing.

Nevertheless, air is not "nothing", but is made up of various molecules, mainly nitrogen and oxygen, which move freely in space. However, these molecules are unimaginably small, so that there is still a lot of space, i.e. empty space, between them. The weight of air must be incredibly small. However: 1 cm³ of air still contains around 1016 Molecules.

What does air actually weigh? - An experiment

Of course, you can't just put the air on the scales, for example in your room. The air in a large room weighs about as much as an adult, i.e. around 70 kilograms - but it is finely distributed in the room.
To determine the weight of air, physicists use complicated and very sensitive scales or devices. For example, the air in a balloon can be measured indirectly via its buoyancy.

Isn't the earth a good weight? Of course, you can't see the globe ...

  1. But a simple experiment can make it clear that even a small amount of air definitely has weight. First, mark the center of the stick.
  2. Then place the pencil over the two tin cans, leaving a gap.
  3. Across this comes the rod that should lie horizontally.
  4. Now tie one of the balloons to each end of the stick with a small piece of adhesive tape.
  5. Check that the rod is still level. The balloons should weigh the same.
  6. Now take one of the two balloons away and blow in as much air as you can. Make sure that no droplets of saliva get into the balloon.
  7. Reattach the balloon to the rod, which is now tilting on its side. Conclusion: Even this little bit of air weighs something!

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