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Solubility of several substances

  1. Dec 19, 2011 #1
    are these soluble in water?

    Na2Cr2O7 (i think yes)

    (NH4)2Cr2O7 (i think yes)

    PbCr2O7 (i think no)

    CuI2 (no? whay is this disproving by rule that iodides and chlorides are soluble in water except for heavy metals?)
     
  2. jcsd
  3. Dec 20, 2011 #2

    chemisttree

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    Maybe copper is a heavy metal?
     
  4. Dec 20, 2011 #3

    Borek

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    There is no such compound, so it is hard to say if it is soluble.

    This is a very specific case.
     
  5. Dec 20, 2011 #4
    so this was the equation i was given: KI + CuSO4---> something

    i assumed it was k2S04 and CuI2

    this is supposed to be either no reaction or double repleacement

    maybe having the whole equatoin helps?

    but the other three were correct, right?
     
  6. Dec 20, 2011 #5

    Borek

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    Actually it is neither. And it is really not that difficult to check, some googling should help you quite fast.

    Yes.
     
  7. Dec 20, 2011 #6
    so if i cancel out spectators, it is a synthesis reaction (most sites agree that cuI2 is insoluble in water)

    Cu +2 (aq) + 2I -1(aq) ---> CuI2 (s)

    what i dont understand is why it is disproving my solubility rule (iodides are insoluble except for heavy metals, and copper isn't a heavy metal).

    ps. you can be awful at googling. if i was good at it i would probably not have to ask these questions here.
    :(
     
  8. Dec 21, 2011 #7

    Borek

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    Show me one site that lists CuI2 as insoluble.
     
  9. Dec 21, 2011 #8
    hte site of the sheet that my teacher gave me. it says "ss" for slightly soluble which he told us to assume meant insoluble. but i gues the chart isnt that reliable. because llokibng now at the other ones i see mostly blanks but one or two say soluble. thanks...
     
  10. Dec 22, 2011 #9

    Borek

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    Are you sure it shows solubility of copper(II) iodide and not solubility of copper(I) iodide?

    In water solutions in the presence of iodides copper(II) oxidizes iodides to iodine and gets reduced to copper(I), this is followed by copper(I) iodide precipitation. CuI is weakly soluble, CuI2 doesn't exist.
     
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