who told me water vapour is lighter than air?

Former Member

come on own up ...i know the orinal post was about 8000 posts ago but come on ...own up.

Former Member

J's right y'know Roll - water vapour is lighter than the air. Otherwise there would be no logical explanation for how it can stay in the sky.

A trip down memory lane.

Former Member

Wait, how can oxygen weigh more than water? Waters got two hygrogen atoms stuck to it to.

Former Member

Originally posted by bongbudda
Wait, how can oxygen weigh more than water? Waters got two hygrogen atoms stuck to it to.

hydrogen atoms are very light (its atomic weight it 1 i think)

Former Member

Yeah, I've had another think about it, the hydrogen is lighter, so it lifts up the oxygen, making it lighter.

Skive

Most of the oxygen in the air is found as O2 and as O3 (ozone) in smaller amounts.

I think you'll find that the reason water vapour stays in the air has more to do with the density of water vapour, temperature, and air currents rather than atomic weight.

Dust, hail and snow are definately 'heavier' than air but that doesn't stop us getting dust clouds, snow and hail does it?

Former Member

Originally posted by z0ma

A trip down memory lane.

mmm ...just say no kids!

Former Member

Surely its to do more with Intermolecular Forces? (A Level Physicist Here but it IS 2:00am and I have just done a 9 hour shift at work). If intermolecular forces are higher then the compound is going to be denser and as such the least dense materials will rise. Also bear in mind that air is a mixture of gases of which Nitrogen makes up the majority. Not entirely convinced it is purely to do with atomic weight.

Former Member

Because your saying that H20 is lighter than O2 because it rises up through it which is to do with density, so yes it does fucking matter. Also that is not normally how you would work out molecular mass unless you wanna tell me how you can count an exact number of molecules and know you only have that many molecules.