Preparation of concentrated solution of HCl

In article <lmreb.14731$[Only registered users see links. ]>, "Simon Dexter" <[Only registered users see links. ]> wrote:

Buy it conc if you want it conc.
Note that HCl forms an azeotrope with water if you distill it. I think it's
known as "constant boiling" HCl amongst other things ... about 6 moles/L IIRC.

Bruce

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If I have a very dilute solution of HCl, may simply distill water (not all
of it) and leave HCl behind? No one wants concentrated solutions of HCl in
labs. I wanna have one.

"Simon Dexter" <[Only registered users see links. ]> wrote in message news:<lmreb.14731$[Only registered users see links. ]>.. .

the system water/HCl is an azeotrope, so distilling won't go past...
uhm.. i think 37% ... not sure about that number tho.

Eryk Remiezowicz wrote:

No no, the azeotrope is something like 20-22%.

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Bernhard Kuemel <[Only registered users see links. ]> wrote:


The constant boiling acid is 20%, roughly.

Steve Turner

Real address contains worldnet instead of spamnet

Bernhard Kuemel <[Only registered users see links. ]> wrote in message news:<[Only registered users see links. ]>...

I agree with you, the aceotrope is about 20 %. To produce concentrated
HCl (> 27 %) you need to upgrade the "dilute one" (< 25 %) by
introducting gaseous hydrochloride into the solution. Even if you try
to distill aqueous HCl with more than 25 % it will loose gasoeus
hydogenchloride up to the aceotropic concentration.

>

Yep, 20 % is what you get by distiling HCl solution at atmospheric
pressure. If you start with lower concentrations, water (and diluted
HCl solution) will distill first, then 20% HCl, at 110C. If you start
with more concentrated stuff, HCl gas (wet) will go first, until you
reach 20% in the heated dist. flask.

One would have to add conc. H2SO4 to the obtained 20% soln. and
re-distill to get more concentrated stuff.

Commercial HCl is about 35-37%, because this is the highest
concentration that does not develop too much HCl gas pressure at room
temp. But they prepare this solution by dissolving HCl(g) in water.

Dear Muhammar:

"Muhammar" <[Only registered users see links. ]> wrote in message
news:a6cffac9.0310012249.296b192e@posting.google.c om...
....

Not that you'll probably care, but cotton seed is commonly delinted by
exposing the fuzzy seed to heated anhydrous HCl, and then neutralizing with
anhydrous HN3. I wonder why the tin sheds this equipment is housed in
corrodes so much?

The anit-fungal coating is no great shakes either...

David A. Smith