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The wonders of MgSO4?

  1. Sep 12, 2013 #1
    Background: Phosphorus + Copper Sulfate:

    I know that the following (unbalanced) reaction proceeds from left to right from this reference, possibly with the formation of elemental copper as well.

    P4 + CuSO4 + H2O -> Cu3P + H3PO4 + H2SO4.​

    This reference (which gets the stochiometry and formula slightly different) agrees.

    The net-net is that Phosphorus, Water, and M1SO4 produce (very dilute) H2SO4.

    Question One: Would this work with an alkali such as Magnesium or Calcium Sulfates in place of the copper sulfate?

    P4 + MgSO4 + H2O -> Mg3P2 + H3PO4 + H2SO4?​

    Question Two: It seems unlikely that a weaker acid could make a stronger one, but metathesis is a powerful ally. Can you really mix oxalic acid and magnesium sulfate to produce sulfuric acid and magnesium oxalate? Anyone tried it IRL?

    Thanks for your thoughts,
    Last edited: Sep 12, 2013
  2. jcsd
  3. Sep 12, 2013 #2


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    Staff Emeritus
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    Mg and Ca are not alkali metals. You are one column in teh periodic table over from the alkali metals (Li, Na, K, etc.)
  4. Sep 12, 2013 #3


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    Staff: Mentor

    Highly unlikely. Copper phosphide is very stable and doesn't react with water, which can't be said about other phosphides.

    If you can remove weaker acid anion by precipitating it out of the solution, you can be left with a stronger acid, precipitation being the driving force of the process. It won't let you make concentrated solutions of the stronger acid, but is definitely possible.
  5. Sep 12, 2013 #4
    And yet

    In response to my statement:
    Steamking responded:
    That is true, but I just referred to them as alkalis. I believe the column group containing Ca, Mg, etc. is called the alkaline earth metals. Or maybe that's not what they're called anymore. It has been a long time since I was in class studying.

  6. Sep 12, 2013 #5
    Q1: That's a shame
    Q2: That's actually pretty cool.

    Again I find myself thanking you, Borek.

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