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Acidic Water Molecules

  1. Jan 30, 2008 #1
  2. jcsd
  3. Jan 30, 2008 #2

    DaveC426913

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    Well, if the water is dissociated into H and OH, I guess a preponderance of H would make it acidic. But that H is not a molecule.

    I just went looking in wiki for pH and they talk about H3O+ as a sort of substitute for H, so maybe that's what they're talking about.
     
  4. Jan 30, 2008 #3

    symbolipoint

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    That formula, [tex] \[
    H_3 O^{ + 1}
    \]
    [/tex], represents both an ion and a solvated proton; not a molecule
     
  5. Jan 31, 2008 #4
    What makes things acidic is H+ ions, right?

    That's only correct to a certain extent. When we refer to H+ ions, we refer to the hydronium ion, H3O+ as some have said. This is what makes acidity. You can't have acidity without water. So you can have the most intense acid in the world, with a pH of 1 or something, but if you remove the water content from it, it will not be acidic.
     
  6. Jan 31, 2008 #5
    Just what the authors of the innovations report mean by acidic
    water is not clear to me. To see one example of how the phrase
    "acidic water molecules" is actually used by chemists, go to
    http://www.rsc.org/ej/CC/2001/b103533a.pdf

    Toward the end of the article you read:

    "...When phenylboronic acid is then added to the
    methanol solution water molecules present in the methanol
    coordinate with the boron Lewis acid and become more
    acidic. These more acidic water molecules can now
    protonate compounds 1 and 3 as well as compound 2."

    So, acidic water molecules are simply molecules of water
    that can more easily give up a proton. Note that water is
    not necessary to have an acid. An acid is a substance that can
    take up an electron pair to form a covalent bond.
    For example, boron trichloride (BF3) is
    an acid and combines with such bases as ammonia or ethyl ether.
     
  7. Jan 31, 2008 #6

    DaveC426913

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    I think you meant 7.
     
  8. Jan 31, 2008 #7

    DaveC426913

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    I know it's an ion but isn't a molecule any combination of 2 or more atoms? Or have things changed since I was in H.S.?
     
  9. Jan 31, 2008 #8

    chemisttree

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    By far the most abundant interstellar polyatomic molecule aside from H2 is H3+. Since the proton affinity of H2 is extremely low, this abundant molecular ion is a strong acid and will protonate anything it comes across, including water. This produces the ion H3O+ which has a characteristic far infrared spectrum that can be observed with the proper equipment. This is what is meant by interstellar acidic water.

    Here is a paper on the subject.
     
  10. Jan 31, 2008 #9

    chemisttree

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    Actually, the pH scale can be extrapolated into the negative range. There are reports of -3.6 pH acidic mine waters in Iron Mountain (superfund site) for example.

    Of course, this is nothing compared to the strength of superacids. Search "George Olah" for more information on that subject.
     
    Last edited: Jan 31, 2008
  11. Jan 31, 2008 #10
    Amazing! And sometimes people struggle to find a way to buy some sulphuric acid; there is gratis!
     
  12. Jan 31, 2008 #11

    chemisttree

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    If you don't mind all the heavy metals!
     
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