On Feb 11, 9:44, Joe wrote:
> I wa swaiting for his. You're right. but SO2 can react with O2 and
> moisture in the air to form H2SO4. In fact, that's how sulfuric acid is
(or
> was) prodused commercailly. I certain proportion of H2SO3 is also
produced
> I'm told that it's only a small amount and it's some how removed and
> retreated to form H2SO4.
No, it's not, and never was. There's practically no reaction at room
temperature and pressure. In fact it's very easy to turn SO3 back into SO2
and oxygen. Just leave it alone for a while.
In the normal "Contact process", SO2 is passed over a catalyst at about 500
deg F, usually VO5 (Vanadium Pentoxide, not hairspray) commercially, or
occasionally platinum (in demos) because it *doesn't* normally react with
oxygen. The SO3 is then dissolved in concentrated sulphuric acid (H2SO4)
because it doesn't dissolve very rapidly in water, particularly when warm,
and and the heat of solution would boil water. The concentrated sulphuric
acid becomes fuming sulphuric acid ("oleum", H2S2O7) and cold water is
continuously added to reduce that to concentrated sulphuric acid again.
The other practical[1] method uses very hot concentrated nitric+sulphuric
acid as an oxygen carrier -- again, because the oxidation of SO2 is too
slow and the activation energy would be far too high otherwise. The SO2,
at about 500 deg F (again) combines with NO2 (from the nitric acid) and
water to give H2SO4 and nitric oxide; the nitric oxide is then re-oxidised
to nitrogen dioxide, which in water gives nitric acid again. Now all you
have to do is separate the two acids.
[1] Perfectly practical providing you have some concentrated nitric acid, a
whole lot of stainless steel tubing, a couple of lead vessels (this process
is called the "lead chamber process") and a tower built of acid-resistant
bricks, and a water cooling tower.
> Yes, but that's a lot less S02 than the amount in the batteries. I'm
not
> suggesting that everyone of the room is going to die but if one of the
> batteries ruptures, it will certainly empty the room in a hurry!
There's not much in a battery. The equivalent of about 1/4 teaspoonful of
sulphur at most, and I suspect, much less.
--
Pete Peter Turnbull
Network Manager
University of York
Received on Mon Feb 11 2002 - 16:22:40 GMT