I'm not sure what you mean by 'pure' acid... If you mean pure as
in 'concentrated', you end up with solution in e.g. water of acetic
acid: In the most concentrated form this is sometimes referred to as 'glacial'
acid. Sulfuric acid actually only excists when dissolved in water: SO3 (a
gassous product that forms when burning pure sulfur) in water forms H2SO4
(=sulfuric acid). This can be bought in different concentrations. The most
'pure' form then depends on the maximum solvability of SO3 in water (98%). Wen
dissolving SO2 in stead of SO3, you get sulfurous acid.
hydrochoric acid (HCl) is, in pure form, a gas. It is formed when common
salt (NaCl), reacts whits sulfuric acid. By dissolving this gas into
water, one obtains hydrochloric acid in dilluted aquaous form.
are pure acids that are available in crystalline (i.e. powder) form. The can
be used undissolved in water to use for all kinds of (chemical) processes, but
still it usually only can undergo reactions in aquatic contions. The reason
for this, is that Acids need to have a liquid environment in wich the acid
itself can release a proton : H+, that is the actual acidic component.
basis rest-molecule can the either be disposed os when your acidified product
if produced in the solution as a crystal (filter of the liquid and dry), or as
a gas (fumes can then be resolved bu suction and storage in a liquid form
onder pressure, or in a solution.
Even water itself has acid
properties: H2O becomes H+ and OH-. Since there are no other molecules left in
this 'solution', and the basic characteristics of OH- are equal to the acidic
characterstics of H+, we've defined water as pH=7.
So a reference to
pure acids, usually means a reference to some kind a solution, without
any other substances
mixed in the solution. So no polution with
other chemicals. The need for 'pure' acids by means of fully concentrated
acids in chemistry is for as far as I know, only needed very sometimes in very
specific processes... When pure acid is mentioned, be sure te check what
concentration is needed. Dilute stronger acids with pure water (no tap water
bu de-ionised or demineralised water, you the kind I mean.
the most concentrated form of nitric acid and hydrochloric acid, (VERY!!!
carefully) forms aqua regia, king's water. Indeed this acid (it's a mixture of
acids, so no pure acid in terms of 'only one substance dissolved in water'),
but it's still an acid not polluted with other stuff, so in my opinion, you
could still call this a pure acid. Indeed it dissolves and reduces gold and
platinum... But if you're trying to make your own gold- or platinum
solutions.... This would be accompanied by a very loud: DO NOT TRY THIS AT
HOME. Even in the most advanced laboratories, this still is a very complicated
and dangerous process....
I hope to have clarified the term 'pure acid'
a bit from a chemical point of view. Maybe much to complicated for some of
this members, sorry 'bout that!
hope to have answered your question,
but let me know if there are additional questions!
Dirk-Jan (or deejay, since my name is so Dutch, other-language
based people usually cannot pronounce it, and deejay has even in holland been
my nickname since highschool :-))
2008/9/7 Jack Fulton <firstname.lastname@example.org
not Mr. Acid-Expert but 'pure' acid is one unadulterated, or
> with water.
> (And, to be honest, I am not sure
that all acids are miscible with water but
> I'd say they
> Glacial basically means that: without water.
> Formic acid
is what ants lay down as a trail and they consist a bit of that.
Acetic acid (in photography we use a diluted form but can purchase it
> 'glacial') is similar to that in vinegar which is generally a 5%
> Hydrochloric (often times, and in hardware stores called
'muriatic') acid is
> what we have in our stomachs (gastric
> Sulphuric (sometimes in US, 'sulfuric') is used in batteries for
autos in a
> dilute form
> Nitric acid is very strong and able to
> Then a really strong combo of nitric and hydrochloric
(1:3) is called aqua
> regia (king water) and that can reduce gold and
platinum but even though it
> is a mixture of acids I don't think it is
technically an acid.
> Jack F
> On Sep 6, 2008, at 6:59 PM,
Christina Z. Anderson wrote:
> What might be a pure acid?
Glacial? Or sulfuric or phosphoric? Or
> hydrochloric? I
have all four here...
> So you are saying that sodium
ascorbate (isn't that what Vit C is) is
> present to a significant
amount in lemons to make more of a difference than
> the actual acid in
> So the test would be lemon juice against
is what is so useful about this list...
> Christina Z. Anderson
> ----- Original Message -----
From: Marek Matusz
> To: email@example.com
Sent: Saturday, September 06, 2008 7:05 PM
> Subject: RE: gum
> Very informative experiment. I do not
think that effect is due to acidity. I
> would rather put out a
hypothesis that the effect is due to the vitamin C
acid) present in lemon juice. Vitamin C is a strong reducing agent
that would react quickly with dichromate reducing it to Cr (III) and
> gum insoluble. Kind of like a dark reaction in gum, no
light needed. It
> appears as a stain, but it really is not. It is
really a chemical fog.
> ANyways to test acidity one would
use solutions of pure acids.
>> Date: Sat, 6
Sep 2008 15:49:18 -0600
>> From: firstname.lastname@example.org
Re: gum preservatves
>> To: email@example.com
Here it is:
Scroll down to the very bottom past the color
>> I'm not saying it proves anything, but
acidity may account for some
people say are issues with gum, and it is only really meaningful
>> relation to the water control strips done at the same
time with the same
>> amounts of dilution. Otherwise a lot more
tests would have to be done to
If, as Ryuji and Demachy said, there is a reduction to
>> acid with the addition of lemon juice, which I don't
know because I am not
>> chemist, I don't know if
that is speedier or less speedy than dichromate.
>> Christin a Z.
>> ----- Original Message -----
From: "Loris Medici" <firstname.lastname@example.org
Sent: Saturday, September 06, 2008 3:13 PM
>> Subject: Re: gum
>> Now that you say that, I remember the
section about it in the "Learn" part
>> of your former website.
(Adding lemon juice and staining... I'm not making
>> it up
>> Judy's note on sizes was interesting and
real food for thought, BTW.
>> Ryuji's notes also
were interesting -> I mean the probability of citric
>> acid (or
any other organic acids) interacting with dichromate in an
unwanted manner. That powered my original position which was
>> the acidity by not adding alien compounds... (Still
don't know if that can
>> work or not -& gt; I may do some tests
in the future if the exposure times
>> become unbearable to me and/or
I can't do nice casein prints...)
Eylül 2008, Cuma, 1:12 am tarihinde, email@example.com
>> > ...
>> > Have at it, Loris.
I found that the more lemon juice drops
>> > I added to the mix
(with drops of water added to the control
>> > group in the same
proportion) that I got lots of staining of
>> > the highlights and
lower contrast, but with paper negs this
>> > might be helpful to
you--I mean, the lower contrast part.
>> > Step wedge steps were
not too differentiated.
>> > Chris
> ----- Original Message Follows -----
>> > From: Loris Medici
> To: firstname.lastname@example.org
> Subject: Re: gum preservatves
>> > Date: Thu, 04 Sep 2008
21:37:54 +0300 (EEST)
>> >>David & Chris,
that also arrived to my mind just after had
>> >>sent my last
message... Even if I refrain to introduce
>> >>another alien
compound into consideration - as a first
>> >>impression -, it
sounds interesting / promising. You can
>> >>bet I will try
this (with citric acid)as soon as possible!
>> >>Of course
there's also the staining issue... I'll see.
>> >>Chris, do you know
how much lemon juice was Demachy adding
>> >>to his
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