tonyascrizzi@juno.com
Date: 06/09/01-12:06:49 AM Z
> Instead of going through all this, why don't you just pop over to the
> auto parts store and buy some battery acid? Battery acid is sulfuric
> acid. I forgot what the strength is, but it will be listed on the side
of
> the carton. If not, ask the guy behind the counter for a MSDS when you
> buy it. (they must supply it on request).
The standard concentration (SG) of battery acid, H2SO4, is 1280 as sold
by many auto and battery supply houses. You may find some 1260 and on
rare occasion some 1300.
>
> Messing around with old batteries can be dangerous. Besides, the
> chemistry going on inside a battery is not pure. There will be trace
amounts
> of lead, tin, antinomy, copper and some other stuff floating around in
it. I
> think the cost for a liter of battery acid was about $4.00 the last
time I
> looked.
If you are indeed messing around, you deserve what you get. :) Practice
safe handling and have fun learning, USE SAFETY GLASSES! And for the
extreme, latex gloves and a rubber bib. Anything organic, (cotton) will,
upon contact with H2SO4 will disentergrate in minutes.
> 1. How do I refine the acid from the batteries to get relatively
> pure sulfuric acid?
If you do not want to actually buy some, used lead/acid batteries can be
of use, but there is a catch. A fully charged battery will have a SG of
1280-1300, but a old discharged battery will read only 1100 or even
lower. Without getting too far off topic, when the battery is discharged,
the sulphur ions are contained within the plates of the battery while a
fully charged battery has little acid in the plates.
If you do decide to get your acid this way, get an old battery and charge
it untill the acid is about 110 degrees. This will indicate severe
overcharge and the acid will be at it's strongest. If the acid is cloudy,
(lead particulate) you may either filter it out using a coffee filter or
simply wait until it settles naturally in a few hours. Using a
hydrometer, test for the strongest acid in the cells and then remove the
desired amount.
Pure H2SO4, Oil of Vitriol, is extremly nasty stuff. A single drop of
water in this acid will cause the water to steam instantly and spatter
acid all over. If you dont mind this and want to work with it anyway, mix
the acid VERY slowly in water contained in a crockery pot with a glass
rod, use no metals and especially no glass containers for mixing! Even
Pyrex will crack.
> > > 2. How do I measure the purity / strength of the acid? Is pH
> the best guide?
Use a hydrometer, available in any autoparts store. Depending on the
method used
to make the acid, there are different trace metals disolved in it,
however they are a tiny fraction and are generally ignored. The acid will
disolve or etch into almost everything except carbon.
Tony Ascrizzi - Electric Vehicle Systems
34 Paine St.
Worcester, MA 01605 (508) 799-5650
Web Page -->http://ElectricVehicleSystems.com
President -->New England Electric Auto Association
http://www.eaaev.org
This archive was generated by hypermail 2b30 : 07/12/01-11:41:54 AM Z CST