[Gasification] Gasification Digest, Vol 19, Issue 10

[Kevin Chisholm]

Dear Mark

Loss of H2 from the balloon has two favourable factors going for it... 
gas osmosis/Diffusion and pressure.

Osmosis is normally thought to be associated with liquids, where a 
solute will migrate through a semi-permable membrane. See:
http://en.wikipedia.org/wiki/Osmosis.

Diffusion is explained very well at:
http://www.mun.ca/biology/Osmosis_Diffusion/tutor2.html.

The pressure difference enables the diffusion process to proceed faster, 
and more completely.

Best wishes,

Kevin




Mark Ludlow wrote:
> Andy,
>
> Andrew is most often spot-on in his replies but your question got me
> thinking. The reason that your hydrogen left your balloons was that 1.) its
> molecular radius is so small that it easily traversed the broader molecular
> matrix of your latex balloons and it headed toward a lower pressure (lower
> H2 partial pressure) destination.
>
> But why, one could ask, did not stray H2 molecules in the air find their way
> into your balloon?
>
> And that suggests 2.), that partial pressure of H2 inside the balloon is
> greater than that outside of the balloon. The separation of species is
> dependent on a relative pressures. H2 cannot flow from a low concentration
> pool to a high concentration pool unless there is a partial pressure
> gradient of the selected gas from a high pressure in the balloon to a lower
> pressure in the receiving reservoir.
>
> In theory, if you had a high pressure reservoir of mixed gasses and a
> membrane with apertures sized to exclude everything except H2, the H2 would
> flow to the receiving reservoir as long as the partial pressure of H2 in the
> source reservoir exceeded that of the receiving reservoir.
>
> I hope I have this straight!
>
> Mark
>
> -----Original Message-----
> From: gasification-bounces at listserv.repp.org
> [mailto:gasification-bounces at listserv.repp.org] On Behalf Of andy schofield
> Sent: Saturday, January 12, 2008 7:37 PM
> To: gasification at listserv.repp.org
> Subject: Re: [Gasification] Gasification Digest, Vol 19, Issue 10
>
>
> Dear Andrew,
>  
> If you don't mind, while you still have your teaching hat on, couldn't
> hydrogen be seperated from other gasifier products by filling a sutable
> vessel with the mixture, and just waiting a long time until the hydrogen
> alone leaks out? The leaked hydrogen could be collected in a surrounding
> vessel constructed of different material. I understand hydrogen particles
> are very small. My brothers and, I used to capture hydrogen in toy balloons
> from hydrocloric acid attacking old steel nails we found. We noted the
> balloons no longer floated in air after a day or so :( 
>  
> Andy
>       On Fri, 11 Jan 2008 11:28:06 -0600, Greg David wrote:    I was
> wondering if hydrogen will separate from wood-gas that is left  to settle in
> a large vessel, because of specific gravity.    No because all materials in
> a gaseous state exert a partial pressure, this means all the individual
> molecules freely intermingle and mix in proportions to their partial
> pressure in the mixture.   AJH
> _________________________________________________________________
> Put your friends on the big screen with Windows VistaR + Windows LiveT.
> http://www.microsoft.com/windows/shop/specialoffers.mspx?ocid=TXT_TAGLM_CPC_
> MediaCtr_bigscreen_012008
> _______________________________________________
> Gasification mailing list
> Gasification at listserv.repp.org
> http://listserv.repp.org/mailman/listinfo/gasification_listserv.repp.org
> http://gasifiers.bioenergylists.org
> http://info.bioenergylists.org
>
>
> _______________________________________________
> Gasification mailing list
> Gasification at listserv.repp.org
> http://listserv.repp.org/mailman/listinfo/gasification_listserv.repp.org
> http://gasifiers.bioenergylists.org
> http://info.bioenergylists.org
>
>