--- In
Homebrew_PCBs@yahoogroups.com, "Stefan Trethan"
<stefan_trethan@g...> wrote:
> On Tue, 23 Aug 2005 12:08:57 +0200, bdl7431 <bdl7431@s...> wrote:
>
> > However, the salt formation has me a bit puzzled - where did this
form -
> > all
> > over the container or around the lid?
> > Bruce
> > PS: I am a chemist in my real life.
>
>
> It has me puzzled too.
> Not around the lid, all over the bottle, under and maybe also above
liquid
> level inside.
> Also, the HCl bottle appeared to get small protruding dimples after
> several years, which is why i hadn't refilled it last time but
instead got
> a new one.
>
> I have no idea what the salt is, i am only guessing it is salt. It's a
> white powder and somewhow it feels like a very fine salt to the touch.
> My workaround (to prevent getting it on my fingers) was to cut off a
> larger bottle and use it as a sleeve around the bottle. Also, i
found if i
> keep the HCl bottle really close to spray cans this isn't good, as
they
> will rust at the seam. Note that the lids on those bottles are very
> reliable, i'm sure the acid traces came "through" the bottle.
>
> Those are the standard-issue bottles at my chemicals store, so i use
them
> for lots of stuff and don't see this problem with anything else,
only with
> white spirit there was a problem too, it evaporated throught the
bottle in
> an amount that would cause it to deform inwards, i use a glass
bottle for
> that now. I am surprised petrol doesn't evaporate through jerry cans
then,
> maybe those are PP and not PE, no sure. Haven't observed any
contraction
> of the can with those.
>
> I would look forward to any guesses you might have as to what this
salt
> might be, i've tried to find out but nobody came up with an
explanation so
> far.
>
> ST
I guess this salt can be ammonium chloride (NH4Cl)
I stored two HCl PE bottles for about 2 years and noticed
a thicker salt deposit on one of these bottles
It puzzled me because these bottled were otherwise identical
But one of them was standing near an ammonia bottle... and salt
deposit was nearly twice as thick as the other bottle
It easy to show: just open an hydrocholic acid and ammonia bottle
near each other, when HCl and NH3 mix in the air it forms whitish
NH4Cl fumes
I guess HCl and NH3 gas can slowly diffuse through PE and form NH4Cl
on surface.
Deposit was seen only on hydrochric acid bottle on all the area
This phenomemnon also shows with an HCl bottle alone as air contains
small quantities of ammonia gas but salt growing is much slower