I do not recommend filling toys with explosives.

and NOT for party balloons.

I want to send up a small camera.

Why does anyone think that someone on DU would even think of such a thing?

I know how fast helium leaks and since it's a noble gas, there isn't much left here, on earth.

I used to weld with it, actually have used hydrogen too, different process.

Like I said, I can make hydrogen, just wanted to know if it leaks faster or slower through the pores in the rubber.

The relevant diameter is the diameter of the electron cloud surrounding the atom/molecule. Unless you're at Hindenburg scale, you won't notice a difference. The difference is very small, and more importantly the distance at which those electrons interact with the electrons in the balloon's molecules are not that different.

And I do not recommend filling balloons for small cameras with explosives either.

I live on 30 acres, it's not going anywhere.

Where's everyone's sense of adventure?
Lost in 9-11? The amount it takes to fill a small balloon won't hurt anything.
Even if it all leaks out. It goes up ^^^.

I should probably record it, eh?

Just in case...

But on the other hand show your 'fireworks' display if not

man, you don't spend much time around here, do you ?

DU has its own coterie of cranks, trolls, and wanna-be Florida Men.

Here, hold my beer ! *BANG* OWWWW!!

since not long after 9-11.

This IS the science forum, right?

I haven't gotten any science answers, yet.
Everyone seems concerned about my usage of hydrogen, which I probably won't anyway.

I was only curious about the freaking size of a helium atom vs. the size of a hydrogen molecule.

In angstroms, please. Or inches, you know.

Didn't really mean to start a big brouhaha.

And nobody holds my beer for nuthin'.

Can you imagine a kids' birthday party full of smokers? Every time a kid popped a balloon near an adult, there would be a fast whoosh of combusting hydrogen. Not good.

Hindenburg

We tested the leak rates of cast aluminum wheels with a vacuum tester and He. We vacuumed out the centers of wheels and injected Helium at 1 atmosphere around the outside.
Helium passes through 10 mm of solid aluminum every time. By measuring the rate of passage we could calculate the porosity of the wheel whether it would fail in the field.
He and H2 will both pass through the wall of a commercially produced toy balloon. The minute difference between the molecules is of far less consequence than the difference between the pressures on either side of the Balloon's membrane. The greater the difference, the greater the leak.

I'm 65 and have been using the stuff for a while, just never in balloons.

It was something that just came to me and needed an answer.

Thanks again.

The other problem is that hydrogen gas is explosive - see "Hindenburg."

Helium is much more inert than hydrogen and shares properties of other noble gases. Hydrogen shares properties of lithium, sodium, and other elements in the 1st column.

I've exploded it before, really loud.

Bad, but not the big BANGS! of people filling balloons with a perfect mix of hydrogen and oxygen from electrolysis.

Can still be bad:

In my experience (I was young and foolish...) pretty much the same as helium leakwise, when it's not burning.

See Graham's law.

If you're just filling a balloon, it will diffuse slowly enough for a "launch". The US Army supplied its weather forecasters with weather balloons and H2 generators; still does, for all I know. Just appreciate that a mass of H2 sufficient to lift a payload will release a lot more energy if it ignites.

If the weight of the payload is small enough, the balloon will rise to an altitude where pressure is low enought that the internal pressure of the balloon will cause it to burst, IF you fully inflate the balloon. A neat way to return your camera, if you include a parachute. Large high-altitude balloons are usually big bags which don't inflate fully -- in fact they are usually left OPEN at the bottom so that helium can escape as the balloon inflates with increasing altitude.

If you're really interested in launching balloons to high altitude, stay away from airports, and familiarize yourself with applicable regulations.

Finally, it may be safer to go commercial ... see e.g. http://www.highaltitudescience.com/products/eagle-pro-near-space-kit

"Gas Permeation in Rubbery Polymers"

Here we go, something from the Zeppelin age:

They say hydrogen leaks about 1.4 times faster... Except for "skinned" fabrics that leak hydrogen and helium at similar rates.

Got this too:



I guess that would be through your o-rings and stuff. Helium seems more misbehaved.

And this, about silicone:

https://www.permselect.com/membranes

Curious numbers, those.

How porous an envelope is, that is, any actual pores or "holes" where Grahams Law becomes more important, now there's another question.

The kinetic diameter of H₂ and He are similar, 289 and 260. The H₂ is "bigger" if you please, more likely to hit something or get hit.

Complications, complications...

Living in farm country, you can use ammonia gas. It's flammable AND it can still kill you even when it's not burning.

http://www.alifeintheair.com/#!flying-on-fertilizer/c1b2p

ammonia, eh? No thanks. the stuff smells.

Never saw it explode, didn't know it would.
Why would you, anyway...and it's harder to make?