Is HC2H3O2 strong or weak

authormessagefamser



Registration date: 07/02/2006
Posts: 8

Posted: 02. Jul 2006 12:50 Title: Titration strong acid - weak base

Hello,
can someone tell me what the titration of a strong acid with a weak base looks like, or post a link where the titration curve is shown?

I only ever find examples where weak is titrated with strong, but never strong with weak (probably not used in practice, right?)

Well, it would be nice if you can help me!
Cyrion



Registration date: 11/10/2004
Posts: 4719
Place of residence: K├Âlle
famser



Registration date: 07/02/2006
Posts: 8

Posted: Jul 03, 2006 5:17 PM Subject:

But both ammonia with hydrochloric acid and ammonium chloride with caustic soda are not strong-weak but weak-strong, right?

I mean, what would e.g. a titration curve of NaOH with acetic acid look like?
Yorkshireman



Registration date: 06/24/2006
Posts: 61
Lives in: Leeds, UK
Posted: Jul 03, 2006 5:32 PM Subject:

Just as if you were using vinegar. and titrate with NaOH. It just begins at the unfamiliar pH end.

Or take a look here:
http://cwx.prenhall.com/horton/medialib/media_portfolio/text_images/FG02_17.JPG

Titration of acetic acid (CH3COOH) with aqueous base (OH-).

As aqueous OH- is added to a solution of acetic acid (CH3COOH) the pH increases. At the start, all of the acetic acid is in the acid form. There is an inflection point (a point of minimum slope) at the midpoint of the titration, when 0.5 equivalent of base has been added to the solution of acetic acid. This is the point at which [CH3COOH] = [CH3COO-] and pH = pKa. The pKa of acetic acid is thus 4.8. At the endpoint of the titration, all the molecules of acetic acid have been titrated to the conjugate base, acetate (CH3COO-).

The pH = 8 at the end of the titration because some of the acetate ions hydrolyze water in reforming acetic acid. The shape of the curve follows the Henderson-Hasselbach equation.

http://chemistry.beloit.edu/Rain/pages/titr.html
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John, Yorkshireman
Oxonium



Registration date: 09/28/2005
Posts: 49

Yorkshireman



Registration date: 06/24/2006
Posts: 61
Lives in: Leeds, UK
Yorkshireman



Registration date: 06/24/2006
Posts: 61
Lives in: Leeds, UK
Posted: Jul 03, 2006 6:18 PM Subject:

or search with google
after "titration curve" under IMAGES and approx. 500 graphs with all possible titration curves appear.
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John, Yorkshireman
famser



Registration date: 07/02/2006
Posts: 8

Posted: Jul 03, 2006 10:03 PM Subject:

york, you wrote NaOH + CHHHCOOH as well as CHHHCOOH + NaOH, only the other way around. with the latter, a buffer solution is initially created, but that's not the case with NaOH + CHHHCOOH after the equivalence point, is it?
Yorkshireman



Registration date: 06/24/2006
Posts: 61
Lives in: Leeds, UK
Posted: Jul 03, 2006 11:29 PM Subject:

The equivalence point is the same in both cases.
Take a look at the cases on the web pages mentioned. You will find everything there.
There is even an Excel sheet for simulating Titr on the website of the University of Lausanne. Curves of all possible cases.
Together with the hints given by other people, you really only have everything you need.
Do not despair, everything will become clear to you.
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All the best!
John, Yorkshireman