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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: grs35 on April 21, 2012, 04:52:36 PM

Title: hydrogen vs. helium
Post by: grs35 on April 21, 2012, 04:52:36 PM
hydrogen is lighter than helium. we know that helium goes up to the sky and leaves the atmosphere. that's why helium is extremely important. if we run out of it it's hard to find it.

if H is lighter than He, why don't we talk about the same problem ? is it because that H is abundant ? or is there any other reason(s) ?
Title: Re: hydrogen vs. helium
Post by: Borek on April 21, 2012, 10:00:56 PM
What are sources of both elements?
Title: Re: hydrogen vs. helium
Post by: billnotgatez on April 21, 2012, 10:54:03 PM
Quote
we know that helium goes up to the sky and leaves the atmosphere
Leaving aside the relative truth of the this statement --
What is the reactivity of helium versus hydrogen?
Title: Re: hydrogen vs. helium
Post by: Arkcon on April 22, 2012, 01:46:34 AM
Another way to help you understand this for yourself, is to look into our isolation methods for these and similar elements.

http://en.wikipedia.org/wiki/Noble_gas#Occurrence_and_production
Title: Re: hydrogen vs. helium
Post by: grs35 on April 22, 2012, 03:23:15 AM
Quote
we know that helium goes up to the sky and leaves the atmosphere
Leaving aside the relative truth of the this statement --
What is the reactivity of helium versus hydrogen?

helium is not reactive and hydrogen is almost every molecular compound.
Title: Re: hydrogen vs. helium
Post by: grs35 on April 22, 2012, 03:28:30 AM
What are sources of both elements?

i know that helium is abundant in the USA. Hydrogen is everywhere.
Title: Re: hydrogen vs. helium
Post by: Borek on April 22, 2012, 03:44:05 AM
i know that helium is abundant in the USA.

Is it?

http://www.chemistry-blog.com/2012/04/19/helium-for-balloons-but-none-for-my-nmr/
Title: Re: hydrogen vs. helium
Post by: grs35 on April 22, 2012, 03:49:47 AM
i know that helium is abundant in the USA.

Is it?

http://www.chemistry-blog.com/2012/04/19/helium-for-balloons-but-none-for-my-nmr/

i meant it is "only" found in the USA. sorry for generalization.

i haven't read this before, but i have watched the video of Martyn Poliakoff on periodicvideos. but again, if hydrogen is lighter than helium why aren't we worried about its escape out of the atmpsphere ?
Title: Re: hydrogen vs. helium
Post by: Arkcon on April 22, 2012, 03:58:40 AM
Regarding the abundance of these two elements, is there a lot in the atmosphere?  Are they found somewhere else?  We've asked you (kinda) to support your supposition

Quote
we know that helium goes up to the sky and leaves the atmosphere
Leaving aside the relative truth of the this statement --

Where did you hear, from a scholarly source, that these gasses float away out of the Earth's atmosphere?
Title: Re: hydrogen vs. helium
Post by: grs35 on April 22, 2012, 04:12:15 AM
Regarding the abundance of these two elements, is there a lot in the atmosphere?  Are they found somewhere else?  We've asked you (kinda) to support your supposition

Quote
we know that helium goes up to the sky and leaves the atmosphere
Leaving aside the relative truth of the this statement --

Where did you hear, from a scholarly source, that these gasses float away out of the Earth's atmosphere?

helium is not a lot on earth. it's one of the main elements that is found in the Sun. and i know how it was discovered. that's why the name helium was given. "helios" is "sun". and it was a misprediction to give -ium as suffix because helium is not a metal. it would be wise to give the name "helion" just like the other noble gases.

there are abundance tables for elements on internet. and in the article Borek gave above and in other sources, it is said that helium rises up and leaves the atmosphere. so it's a fact. and if it is lighter than air, it's a fact that we can not argue.

i haven't read about hydrogen's leaving the atmosphere. but if it is lighter than helium (which is another fact) we must be talking about hydrogen's escaping the atmosphere.

Title: Re: hydrogen vs. helium
Post by: Arkcon on April 22, 2012, 07:43:01 AM
You've compiled a vast collection of supposition, just to prove an arbitrary point of your own.  And you insist that we support it.  So I don't know where this discussion is going to go ... however.

The Earth loses tons of its atmosphere, and has been, since it formed.  However, like other planets that allow life to evolve, it has a supply that takes billions of years to deplete by this method:  http://en.wikipedia.org/wiki/Atmospheric_escape#Dominant_atmospheric_escape_and_loss_processes_on_Earth

There's no diatomic hydrogen in the Earth's atmosphere, because its reactive enough to form compounds.  All the hydrogen you've found lying around came from decomposition of Earths water, supplies of which are vast on the scale of "floating away" depletion that you describe.  Probably much of the lost hydrogen re-enters the hydrological cycle, oxizied by some atmospheric process.  The planets Mercury and Venus lost all their lighter elements because they have no cyclical processing and the solar wind was able to ionize and strip it away.  But even in those cases, it didn't simply flow away.

Earth's atmosphere is not stratified by component density.  You assume the hydrogen and helium are floating like corks to the top of the atmosphere and flying away.  That's simply not the case.  If it were, then denser gases should be accumulating at our feet.  Even without the wind, a "solution" of gases doesn't stratify in that way, any more than a salt water solution ends up with a "pile" of Na+ ions on the bottom, under a layer of CL- ions with the water on top, the mixture is in constant molecular motion to keep it mixed.
Title: Re: hydrogen vs. helium
Post by: grs35 on April 22, 2012, 05:03:38 PM
You've compiled a vast collection of supposition, just to prove an arbitrary point of your own.  And you insist that we support it.  So I don't know where this discussion is going to go ... however.

The Earth loses tons of its atmosphere, and has been, since it formed.  However, like other planets that allow life to evolve, it has a supply that takes billions of years to deplete by this method:  http://en.wikipedia.org/wiki/Atmospheric_escape#Dominant_atmospheric_escape_and_loss_processes_on_Earth

There's no diatomic hydrogen in the Earth's atmosphere, because its reactive enough to form compounds.  All the hydrogen you've found lying around came from decomposition of Earths water, supplies of which are vast on the scale of "floating away" depletion that you describe.  Probably much of the lost hydrogen re-enters the hydrological cycle, oxizied by some atmospheric process.  The planets Mercury and Venus lost all their lighter elements because they have no cyclical processing and the solar wind was able to ionize and strip it away.  But even in those cases, it didn't simply flow away.

Earth's atmosphere is not stratified by component density.  You assume the hydrogen and helium are floating like corks to the top of the atmosphere and flying away.  That's simply not the case.  If it were, then denser gases should be accumulating at our feet.  Even without the wind, a "solution" of gases doesn't stratify in that way, any more than a salt water solution ends up with a "pile" of Na+ ions on the bottom, under a layer of CL- ions with the water on top, the mixture is in constant molecular motion to keep it mixed.

thanks a lot. this is really helpful. i appreciate this detailed information that you gave.
Title: Re: hydrogen vs. helium
Post by: sixrings7keys on April 24, 2012, 01:27:05 PM
Helium is created through radioactive fusion. If you use radio-spectroscopy to view the earth and see helium bubbling from a certain point..I guarantee you will find some radioactive metal there such as uranium.