Gases around us

[June10]

Which has more weight and why - an inflated balloon or an empty balloon

[Law Student]

The balloon itself always weighs the same. Any change is caused by the difference in density of the inflating gas compared to air. So if the balloon is full of air, there's absolutely no difference at all.

[whowhatwhy]

depends what you inflate it with. If you blow into it....then i suspect it will be heavier due to the presence of water vapour in the breath and higher levels of carbon dioxide. Also air will be held under slight pressure within the balloon, therefore the gas will be slight compressed, occupying slightly less volume than it would under normal atmospheric conditions, increasing the weight of the balloon slightly, relative to the volume of air it displaces. But that's a really anal response.

Basically there the same!

[whowhatwhy]

sorry, they're the same....i meant.

[mibn2cweus]

Buoyancy affects measured weight in which case the above answers are correct where the same type and density of gas is found within and outside of the balloon, however, (as whowhatwhy mentioned) the elasticity of the balloon will compress the internal gas slightly thereby giving the gas inside a slightly greater pressure/density, reduced buoyancy and therefore slightly increased weight when inflated.

Helium has a lower mass/density than an equal volume of air under similar pressure and therefore increases buoyancy and reduces the weight as measured in a standard atmosphere (even after slight compression).

When measured within a vacuum (where buoyancy is no longer a factor) the contents of the balloon will increase its measured weight in direct proportion to the mass of the added contents, however, with no external pressure a comparatively small quantity of gas will rupture the balloon.

whowhatwhy, guess I better wipe after that one!

[mibn2cweus]

. . . perhaps I should add . . . if one is sufficiently full of hot air this will tend to counteract the compression effect of the balloon and in theory could cause the balloon to float for a time until the heat dissipates.

[ugly_bob]

Technically, an inflated balloon will actually weigh more. Whatever it's inflated with.
Since the weight of an object is the force due to gravity, it will increase with anything added (be it air, helium, lead etc).
The problem is,as already said, bouyancy in the fluid containing the baloon. The displacement of external fluid causes a counteracting force. Weight can only be measured accurately in a vacuum

[Gef]

If, by the inflated balloon, you mean the balloon plus the air inside it then it will be heavier (have more mass).

[Gef]

Sorry, meant to add.

Empty balloon - mass of balloon only.
Inflated balloon - mass of balloon plus mass of air.

[whowhatwhy]

"guess I better wipe after that one!"

I am in ore, as usual...I'll pass the paper ;)

[whowhatwhy]

or even awe.