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Why are hydroxides of earth alkaline metals are so insoluble in water?

  1. May 26, 2013 #1
    Why are hydroxides of earth alkaline metals so insoluble in water?
    They are polar compounds and have an OH group, so they should do hydrogen bounds with water, as well as permanent dipole interactions, which in my conception are strong forces.
    Even Mg(OH)2, witch do not have a big mass, has a solubility of just 1,4 mg/100ml
    Can anyone help me to understand this?
    Last edited: May 26, 2013
  2. jcsd
  3. May 27, 2013 #2


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    Science Advisor

    Yes, but the ionic bonding between a alkaline oxide metal with two positive charges and a hydroxyl ion are even stronger (more than twice as strong as in a corresponding alkali metal given that the ionic radii are smaller, too).
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