At 2:01 pm ((PDT)) Wed Apr 11, 2007, Stefan Trethan wrote:
>On Wed, 11 Apr 2007 17:46:35 +0200, DJ Delorie <dj@...> wrote:
> > That reminds me, I still have some sulfuric acid kicking around from
> > many years ago. Is that at all useful in pcb making?
>
>There is an etchant made from sulphuric acid and H2O2 much like CuCl (only
>of course copper sulphate). Sulphuric acid would have some neat qualities
>compared to HCl, but there was some catch making it unsuitable for me,
>which sadly i do not remember. But it is used industrially in some cases.
It is more hazardous in handling than hydrochloric acid:
because it not volatile - so un-neutralized splashes get
more concentrated as they dry, rather than evaporating;
and also, diluting concentrated sulphuric acid is highly
exothermic. (Always add acid to water, not water to acid.)
Conc. sulphuric (98%) is more concentrated than conc.
hydrochloric which is limited to around 40%.
Of other grades, "battery acid" at 33.5% is close to
commercial HCl "muriatic acid" strength.
You may find sulphuric acid sales are more tightly
controlled than hydrochloric acid, since it can be used
to make nitric acid and explosives.
Regards, LenW