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Re: Hydrochloric acid

Hello Richard,

You are absolutely right that *concentrated* hydrochloric acid (25-38%)
is nasty stuff! The fumes choke you and it will corrode almost anything
within reach.

Diluted HCl (about <10%) on the other hand, is much less dangerous. As a
matter of fact, without it we could not digest our food: Stomach acid is
dsilute hydrochloric acid! 

Contrary to some opinions, gaseous HCl does NOT escape from dilute HCl
solutions. That has been demonstrated by about 100 years of using
hydrochloric acid as a standard titrant in chemical analysis.

There is absolutely no need to use the concentrated acid in the
fish-room: Outside (or in front of a good exhaust fan) pour *slowly* 1
cup of acid into 2 cups of water (NOT the other way around!) and use the
resulting solution (about 10% concentration) for water acidification.

Until one gets a "feel" how much acid has to be added to reach the
desired pH, your advice to add the acid drop-by-drop is a good one! 

Keep the dilute acid in a stoppered bottle (glass or plastic, including
the cap) at room temperature and it will be good "forever".



> At 03:48 PM 11/22/98 -0500, you wrote:
> >Thanks to everyone who has been emailing to the list regarding various
> >acids and their advantages and disadvantages.
> >
> >Thanks also to whoever it was that set me straight about acetic acid ....
> >I will not be adding it to my tank!
> >
> >After looking around in a number of places, I finally found a source of
> >Hydrochloric Acid at a hardware store (Most shop keepers looked at me
> >funny when I started to explain that I wasn't really interested in
> >cleaning concrete.....)
> >
> >I found a 5 litre container of Hydrchloric acid (Muriatic - "Spirit of
> >Salt" ???) for $9.95 (Aus)., which sounded like a bargain to me. I'll
> >never have to buy any more - unless it has a maximum shelf life???
> >
> >Anyhow, the label says that it contains 350g/L HCL.  I imagine that this
> >is 350g of HCL in granular form that has been added to each litre of
> >distilled water.  Is this correct?
> >
> >If so, what concentration HCL do I have?  How many drops / ml would you
> >guys recommend adding to SLOWLY lower my pH, considering that the tap
> >water is pH of 8.4 and 120ppm Carbonate Hardness?
> >
> >i do not add CO2 to this tank, I am just trying to lower the pH to a more
> >neutral point.  I am not concerned about the few fish that live in the
> >tank.
> Hydrochloric acid is wicked nasty stuff. First of all it's a solutiojn of
> hydrogren chloride (a gas) in water. It tends to go out of solution
> really easily and the vapour is pure acid fog. You don't want to
> use this stuff indoors without extremely good ventilation. It
> loves to put out vapour.
> 5 litres will last you seevral lifetimes.
> Ad a drop at a time, let it circulate, then take a pH reading.
> You need to carefully add a drop at a time until you see
> a change.
> If you look at an old enoug Guiness Book of Worls Records,
> you'll find HCl listed as the worls stongest acid ('57 sor
> sure, maybe others).
> - --
> Richard J. Sexton                                         richard at aquaria_net
> Maitland House, Bannockburn, Ontario, Canada, K0K 1Y0       +1 (613) 473 1719