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Ferric chloride and ferric nitrate


You chemists out there-- This is a point of confusion, and
curiosity: ferric chkoride and ferric nitrate are not acids, are
they? I was under the impression that they were bases. Am I wrong?
The main reason that this matters is that I want to be sure what to
use to neutralize them, particularly a spill. Thanks!


   ferric chloride and ferric nitrate are not acids, are they? I
was under the impression that they were bases.

Noel, Ferric Chloride and Ferric Nitrate are technically, neither
acids nor bases, but salts. however, both of them represent the
equivalent of a nitric or or Hydrochloric acid solution, which has
been used to dissolve SOME iron, but not to the point of fully
utilizing the acid’s ability to react (which would be 46errOUS
chloride or nitrate). The salts, dissolved in water, are still
highly acidic with a similarly low ph as the original acids, but
because they’ve got some dissolved metal, they are less vigorously
active, thus giving a better/smoother etch with less undercutting,
etc. You neutralize them the same way you neutralize the simple
acids themselves.

Peter Rowe


Ferric Chloride and Ferric Nitrate are inorganic salts Noel and are
very strong oxidizing agents. They are NOT bases! In aqueous
solution Ferric Nitrate dissociates to form Nitric acid and Ferric
Chloride effectively dissociates to form Hydrochloric acid if I
remember correctly that far back. These are the acids that do the

“NOTE: It is against Federal law to dispose of ferric chloride down
the drain. All ferric chloride etching solutions and the rinse water
from the first four rinses must be captured, labeled as Hazardous
Waste, and picked up by Stanford Environmental Health & Safety”.

The above is an interesting little quote from this site:

Ferric Chloride:

Ferric Nitrate:

Al Heywood


Ferric chloride and ferric nitrate are “Lewis acids” For your
purpose they are “acids”

The solution must not be put down the drain because of residual
copper ions left in it. To make it safe for disposal, you can add
sodium carbonate (washing soda) ,sodium bicarbonate( baking soda )or
sodium hydroxide to it to neutralize it, until the pH value goes up
to between 7.0 and 8.0, when the co2 bubbles stop. Copper will be
deposited as a sludge. Allow the sludge to settle, pour off the
liquid, further dilute it with water and then it can be poured down
the drain. Collect the sludge in plastic bags and dispose of it as
required by your local waste authority. In small shop cases usualy
in the trash.

To find out moRe:

and with an etching focus:

Ferric nitrate is handled the same way , but you can knock the
silver out to the sludge with table salt. Both silver and copper are
bad for the the waste water system and toxic to particularly
freshwater creatures. Jesse

ferric chloride and ferric nitrate are not acids, are they? I was
under the impression that they were bases. Am I wrong? 

G’day Noel et al.; Before I try to answer that, let’s have a go at
a general (rather loose) definition of an acid. But I don’t want to
get into complications (there’s many) as I don’t want to confuse or
"blind you with science!"

An acid is a substance which has an easily replaceable hydrogen
atom; HCl; HNO3; H2SO4. It turns certain vegetable colourings
like litmus from blue to red. It has a pH below 7.0 (don’t worry
about the exact meaning of that; it can get very abstruse and
confusing) It has a sour taste. It combines vigorously with
alkalies and bases.

Alkalis have an easily replaceable hydroxyl group; NaOH, KOH etc.
Turn litmus from red to blue, have a pH higher than 7.0, combine with
acids to form a salt. Many salts are neutral, but some are acidic;
others are alkaline. Sodium bisulphate does have a poorly attached
hydrogen atom, so it has an acid reaction. Some salts like sodium
carbonate have an alkaline reaction because carbonic acid is one of
the weakest, and a hydroxyl group becomes available when dissolved in

Ferric nitrate and ferric chloride are both salts within the meaning
of the definition; they are the result of a combination of an acid
and an alkali. But in both of these there is a weakly held hydrogen
atom, and this makes them acidic; they have a pH lower than 7, turn
litmus red, taste acid and combine with alkalis and bases. (metals
are basic; neither acid nor alkaline. Their oxides are another story
and things get complicated)

    The main reason that this matters is that I want to be sure
what to use to neutralize them, particularly a spill. 

From what I have said above, it follows that spilt acids and liquids
of of dubious origin should be neutralised with a mild alkali, such
as sodium carbonate, or sodium bicarbonate.

When I was responsible for the technical operation of chemical
laboratories, I insisted that close to every bench a large wide
mouth 3 kilo jar of sodium bicarbonate must be always available, to
simply tip the contents over any acid spill. The resultant heap can
later be disposed of by sweeping up with a dustpan and brush. This
was used for smashed 3 litre bottles of concentrated acids. It is
the only safe method of clearing up the mess, which can safely be
disposed of in the usual way. For spent jewellers-pickle, neutralise
it with bicarbonate, mix with sawdust or sand, allow to dry, wrap in
newspaper and have it taken to the usual trash tip.

Sodium bicarbonate is very cheap (I used to purchase it by the
hundred weight sack) and is available at any supermarket. “Baking
Powder” is not the same and is not suitable.

Finally, make it an unbreakable rule that all chemicals of any kind
(including table salt and sugar) are clearly labelled, and the label
kept up to date and easily readable. Poisons must be out of reach
of children and clearly labelled. Keep to the rule:- ’ if it is
unlabelled, it MUST be thrown out’ Thinking you know what it is
isn’t good enough. – Cheers for now, John Burgess; @John_Burgess2
Mapua, Nelson NZ


Noel: Both ferric chloride and ferric nitrate are acidic salts. They
are produced by the interaction of strong acids and weaker
bases…for example - Ferric hydroxide [weak base] + nitric acid
[strong acid] -->ferric nitrate [acidic salt] + water

Although weaker than the traditional acids…they are still harmful
and care should be taken to protect yourself, your clothing, etc.

An acid is something that contributes hydrogen ions, H+, to
solution. For example: HCl in water ionizes to H+ + Cl- HCl =>
H+ + Cl- hence an aqueous solution of HCl is acidic.

The ferric nitrate dissociates into both ferric and nitrate ions.
The nitrate ions are strongly soluble, but the ferric ion is only
partially soluble and will weakly dissociate. In a water solution
this means the ferric ions will associate with OH- ions to some
degree, decrease the OH- concentration, and upset the natural balance
of H+ and OH- in water. Less OH- means more H+ in a water
solution…and anything that causes more H+ in a solution is
considered acidic.

Hope this helps a little.