# Thread: Does air have mass?

1. Hi,i was doing one lab at home and i dont know how to do it. It does not tell u how to do it. But i know i can use a ballon for that. But how to measure it does have mass with home instruments.  2.

3. A small vacuum pump arrangement is described in this link.
Perhaps you can assemble a comparable system with some bits and pieces and some ingenuity. This, however, will not measure the mass of air, but simply demonstrate effects that may be interpreted to mean that air has mass.

To measure it I can't think of anything other than a long rod (over thirty feet), sealed at one end, filled with water, then inverted in a container of water. Measuring the height of the column will determine the mass of air above the water level in the container.
Not very practical - but then the most practical thing I ever do is delegate.  4. This is all I can figure out involving a balloon:

1) Weigh the empty balloon (Weight 0)
2) Fill the ballon with air
3) Weigh the balloon full of air (Weight 1)
4) Weight of air = W1-W2
5) mass = W/g (g = gravity acceleration constant = 9.8 m/s^2 = 32 ft/s^3)

You'll need a ballon, and a balance to weigh the ballon... I'm just concerned about the precision of a home balance not being enough for this experiment (air weighs to little, that you won't be able to see anything with a normal balance), You should use the lab's balance to do this.  5. Originally Posted by Cuete
This is all I can figure out involving a balloon:

1) Weigh the empty balloon (Weight 0)
2) Fill the ballon with air
3) Weigh the balloon full of air (Weight 1)
4) Weight of air = W1-W2
5) mass = W/g (g = gravity acceleration constant = 9.8 m/s^2 = 32 ft/s^3)

You'll need a ballon, and a balance to weigh the ballon... I'm just concerned about the precision of a home balance not being enough for this experiment (air weighs to little, that you won't be able to see anything with a normal balance), You should use the lab's balance to do this.
This wouldn't work unless you weighed it in a vacuum.  6. Really? I tought it would work.

You could be right, because the air density is the same in and out the balloon...

Sorry, I can't confirm it, because I haven't tried the experiment.  7. Originally Posted by Cuete
Really? I tought it would work.

You could be right, because the air density is the same in and out the balloon...

Sorry, I can't confirm it, because I haven't tried the experiment.
If you use a balloon, you'd have to weigh in a vacuum unless you mathematically correct for the boyancy of the atmosphere. (Of course, to correct for the boyancy of the atmosphere, one needs to know that air has weight!).

A better method would be to take a hard inflexible hollow container, such as a metal cylinder. Evacuate the air from the cylinder using a vacuum pump (or several other methods!). Weigh the cylinder. Let air into the cylinder. Reweigh. The difference in weight is the weight of the air within the cylinder.  8. fill it up with earth gas, that's heavier than normal air, that should make it heavier..  9. Earth gas? :? Do you mean natural gas? That wouldn't address the issue of measuring a mass of air.  10. Boyle's Law guys.

where:
V is volume of the gas.
P is the pressure of the gas.
k is a constant.

Indeed, in meteorology, air is often referred to as "masses."

Warm Tropical air is either an mT air mass or a cT air mass for maritime tropical or continental tropical respectively. Cold air from the north is frequently referred to as cA or mA air for continental arctic or maritime arctic air respectively. Though there can be cP or continental polar air formed over sea ice.

cP air masses are dryer and heavier than mT air masses. Low pressure systems create upward moving (light) air and high pressure systems create downward moving (heavy) air.

Air has molecules of nitrogen, oxygen, hydrogen, etc and therefore has mass since each of these molecules have mass (see your periodic table). Refer to Boyle's law for the formula.

A quick way to demonstrate that air has mass would be to tie two balloons of equal inflation to the opposing ends of a yard/meter stick suspended in the middle by a string. Evacuate the air from one balloon. Observe the results.  11. Air inside the balloon is compressed as it is stretching the ballon's walls, thus causing a force. Now, if air haves a weight, then air with a higher density (higher pressure) must weight more, thus a balloon filled with air must weight more than the same volume of air, thus it will have a negative buoyancy and will "sink", that is, fall to the ground, if we release it...

If air had no weight, then compressing it inside the ballon would have no effect in its density thus its buoyancy would be the same as for "free" air.

Just a suggestion that doesn't implies precission scales.  12. hmm, i think you are right.. by the way, i'm dutch and "earth gas" is "aardgas" so i translated it wrong..

anyway it's true that pressurised air weights more than unpressurised, it'll be like 0,0001 grams difference

but it'll have to cool down as well, because pressurised air has a higher temperature and will be lighter. Anyway, this difference will even be less.  13. Originally Posted by SkinWalker

A quick way to demonstrate that air has mass would be to tie two balloons of equal inflation to the opposing ends of a yard/meter stick suspended in the middle by a string. Evacuate the air from one balloon. Observe the results.
You are neglecting the boyancy effect. The apparent mass of the balloon is reduced by the mass of the volume of air the balloon has displaced.

So your experiment will not work, except for one factor: The pressure inside the balloon is greater than atmospheric pressure (by 20 % or so in a typical party balloon) due to the elasticity of the rubber compressing the air within. So the density of the air inside the balloon is greater than the air it has displaced. Therefore the air within the balloon has a greater mass than the volume of air that was displaced. As a result, what your experiment is actually demonstrating is that air is compressible and has density. And since density requires mass, as a result you have demonstrated that air has mass.  14. Darn. Thought I had it worked out, too. Still, if you could do the experiment and cool one balloon whilst heating the other, you would notice the difference.  15. but only the balloon and not around it... hehe  16. I remembered my chem teacher told us the relative mass of air is 29,so according to this,you can calculate the actual mass of it.So the answer is positive~  17. I would have said what silylene said about the difference due to compression, but I couldn't think of it.

(Other than that, I had the right idea?)  Bookmarks
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