Acetic acid and vinegar - a bit of chemistry
- Subject: Acetic acid and vinegar - a bit of chemistry
- From: D* M*
- Date: Wed, 5 Jun 2002 15:28:12 -0500
>Hi Marya,
>
> Since concentrated vinegar is considered to be flammable and can
> release toxic gases when heated, I wouldn't recommend doing this
> unless you were in a controlled environment. It can also react
> with certain metals to create hydrogen gas which wouldn't be a good
> thing to have near open flames... :)
>
OK folks. It's not my intention to offend anyone, but I think a bit
of a chemistry lesson is called for here (sorry).
Commercially, acetic acid (HC2H3O2) is produced through the
destructive distillation of wood, the reaction of water and
acetylene, and several other methods. The "pure" form is 99.5% pure
and referred to as glacial acetic acid(glacial = ice-like in
appearance).
The term "vinegar" is generally restricted to designate much diluted
forms of acetic acid (generally 5%) formed by the oxidation of the
ethyl alcohol in wine or fermented fruit juices. Many people use
vinegar as a cleanser for their coffee pots and in this relatively
dilute form, does little if any damage to metal as long as exposure
is not for long periods of time.
Neither acetic acid nor vinegar are flammable, although heating can
vaporize the acetic acid, which is caustic in higher concentrations.
Regarding the production of a 20% solution of acetic acid starting
with 5%, I doubt this would be successful, since the acetic acid in
the vinegar would also vaporize along with the water. The boiling
point of acetic acid is about 118C=244F. Mixtures of this type form
what are called azeotropes (good Scrabble word), meaning mixtures of
two or more substances that retains the same composition in the vapor
state as in the liquid state when distilled or partially evaporated
under a certain pressure. Translated into English, this means that
the acetic acid can only be concentrated to a certain % before both
the water and acetic acid boil off at the same ratio. Unfortunately,
I cannot find this value for mixtures of acetic acid and water, so I
can only say that it "might" work.
Sorry if I've told you More About Acetic Acid Than You Ever Wanted To Know.
--
Don Martinson
Milwaukee, Wisconsin
l*@wi.rr.com
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