Re: Na + H2O2 (50%) -> H2?

From: David Harper (dave.harper_at_gmail.com)
Date: 07/19/04 

Date: 19 Jul 2004 06:14:33 -0700

jedcheck@yahoo.com (Jed Checketts) wrote in message news:<e98177f2.0407182105.3de29d1e@posting.google.com>...
> dave.harper@gmail.com (David Harper) wrote in message news:<364fd697.0407172343.7b5a87c1@posting.google.com>...
> > ZHEN <zhenf@hotmail.com> wrote in message news:<40F9E740.496A99C4@hotmail.com>...
> > > Hi, everyone knows:
> > > Can i use 50% H2O2 to get H2 at room tempeature?
> > >
> > > H2O2 + H2O + Na -> H2 + NaOH + H2O2
> >
> > Before you do that, get all your affairs in order.
> >
> > Ignoring the H2O2 part, you know what happens when you put sodium in
> > water, right? It's extremely exothermic and can be dangerous.
> >
> > Additionally, H2O2 throws off it's extra O relatively easy, so you
> > might end up having the Na + H2O reaction, PLUS extra O2 given off by
> > the H2O2. If you have any free H2 in the area near a hot reation with
> > O2 floating around also, you'll end up with an additional reaction
> > that fuels the space shuttle's main engines: (2H2 + O2) -> LOTSAHEAT +
> > 2H2O
> >
> > If you want H2, go to a local gas supplier and rent a full 200+ ft^3
> > tank for 50$.
>
> The compressed hydrogen route is very expensive. 200 cubic feet of
> hydrogen is just slightly over 1 pound of hydrogen. To spend $50.00
> for this pound is silly when 11 pounds of sodium hydride (at around
> $.75 per pound) would produce the same amount of hydrogen. A bottle
> of compressed hydrogen is also quite bulky and has an initial cost of
> more than $100.00 (not including the expensive pressure regulator) It
> is also very hard to pick up. Most people just try rolling the heavy
> metal bottles along the ground slowly.

(SNIP)

Yes, and when he creates 200 ft^3 of hydrogen, how do you think he'll
store it? In a big balloon? Unless he plans on only using small
portions at a time and using it immediately, a compressed cylinder
affords small volume and no potentially dangerous processing (and
hardware to capture the gas) needed. And if he doesn't need 200 ft^3,
he can just get a smaller cylinder for less.

On a side note, I don't know where you got that 100$ estimate from.
Sure, maybe if you buy it instead of rent it. 50$ is a very
conservative over-estimate. One place quoted me 27$ + 10$ for the
regulator, but I ended up opting for helium instead (60$ per 200 ft^3
cylinder) due to additional safety.