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  1. #11
    gainer's Avatar
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    Quote Originally Posted by titrisol
    What is the composition of KODALK?
    Any ways to replace it?

    Is it borax/boric acid?
    Yes, you can replace it, and no, it is not borax+boric acid. I refer you to www.borax.com. Borax is the accepted common name for Na2B4O7.7H2O. Kodalk is either NaBO2.4H2O or Na2B2O4.8H2O, take your pick. They are equivalent. Above 53 C, NaBO2.4H2O becomes Na2B2O4.8H2O in solution. The mixture of borax and lye I gave above approximates that closely enough for government work.

    Just plain borax will not achieve pH = 10 no matter how much you dissolve.
    Gadget Gainer

  2. #12
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    OK, so is a buffered pH 10 alkali.
    Perfect, borax/NaOH is what I was looking for.
    Thanks guys!
    Mama took my APX away.....

  3. #13

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    [QUOTE=gainer]
    Yes, you can replace it, and no, it is not borax+boric acid.
    I refer you to www.borax.com. Borax is the accepted
    common name for Na2B4O7.7H2O.
    Above 53 C, NaBO2.4H2O becomes Na2B2O4.8H2O in solution.
    [QUOTE]

    Na2B4O7.10H2O; a decahydrate. That 10H2O, as some know, is the
    water of crystallization.

    Vice versa. Above 53 C, NaBO2.8H2O becomes Na2B2O4.4H2O in solution.
    Dehydration occures as the temperature rises. Again those
    H2Os are waters of crystallization.

    From my reading at www.borax.com both hydrates are stable.
    The 4 Mole has a little more ph per pound. Dan

  4. #14
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    Serves me right for not looking it up. Borax is the decahydrate. There is a heptahydrate of sodium carbonate, but it doesn't seem to have a common name. Its decahydrate is commonly known as washing soda. Maybe the fact that my brain's hard drive is 77 years old has something to do with it. This is the age when one may not only forget things, but also forget that he forgot them.
    Gadget Gainer

  5. #15
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    "From my reading at www.borax.com both hydrates are stable.
    The 4 Mole has a little more ph per pound. Dan"

    The table I saw at www.borax.com showed a gradual change of pH with concentration and a transition from 4 mol to 8 mol above 53 C. I can't see how that jibes with what you saw. The molecular weight of the 8 mol is exactly twice that of the 4 mol, but a given weight of either one contains the same number of molecules. I don't think you can crystallize the 8 mol from a solution below 53 C. So far as I can see, the transition is reversible. I don't think there exists a solid NaBo2.8H2O.
    Gadget Gainer

  6. #16
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    I should have said "a given weight of either compound contains the same number of atoms of Na, B, H and O."
    Gadget Gainer

  7. #17

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    Quote Originally Posted by gainer
    "From my reading at www.borax.com both hydrates are stable.
    The 4 Mole has a little more ph per pound. Dan"

    I don't think there exists a solid NaBo2.8H2O.
    At the borax site choose, products and services, then, our products.
    VIEW both the 4 and 8 mole technical info. Stability and solubility
    are of most interest.

    Correct. There is no metaborate as you've mentioned above. There
    is though Na2B2O4.8H2O which will crystallize as such from solution
    at temperatures below 53 C. Above that temperature crystalls of
    Na2B2O4.4H2O will form.

    It's likely they ship both the 4 and 8 mole products. NaBO2 and
    Na2B2O4 are used interchangeably. I could only guess why that
    is so.

  8. #18
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    'At the borax site choose, products and services, then, our products.
    VIEW both the 4 and 8 mole technical info. Stability and solubility
    are of most interest.'


    ...or just click on the link I gave at the start of this discussion to go there directly, but may as well give again here:

    4 Mol

    8 Mol
    Last edited by Helen B; 09-26-2004 at 08:07 AM. Click to view previous post history. Reason: Extreme sloppiness - I missed a dot out of the ellipsis...

  9. #19
    gainer's Avatar
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    Anyway you look at these sites, the number of atoms of Na, B, H, and O that you get by weighing out a gram is the same for either the 4 Mol or the 8 Mol. In solution the water of crystallization just increases the amount of water.

    I doubt that the chance of getting anhydrous NaBO2 when you order sodium metaborate are very good. I could be wrong. It seems I have been wrong a lot lately.

    I had the temperature ranges backward.
    Gadget Gainer

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