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Inorganic chemistry help

  1. Nov 13, 2005 #1

    I'm doing this chemistry report, and I have absolutely no experience in chemistry.

    We have this solution containg (among some other stuff) Ba^2+, Sr^2+ and Ca^2+ ions along with SO4^2-ions in excess. Now we add some Na2CO3 to transform the sulphates to carbonates. They ask me these questions:

    1) Write the reaction equations for this transformation. My guess is:

    BaSO4(s) + CO3^2-(aq) --> BaCO3(s) + SO4^2-(aq)​

    and so on.

    2) Is the solution acid or basic in this reaction? Since CO3^2- is a weaker base than SO4^2-, I would say that the answer is basic.

    3) Calculate the equilibrium constants by using the solubility products. Ok, here I start by writing the equilibrium equation:


    This should be valid for both the Ba-, Sr- and Ca-case. But this doesn't make sense, since the constants should be different. What am I missing here?

    4) Explain why BaSO4 reacts to form BaCO3 even though BaSO4 is sparingly soluble (I hope this is the phrase) to a higher degree than BaCO3. I'm lost at sea here.
  2. jcsd
  3. Nov 9, 2016 #2


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    Science Advisor
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    Gold Member

    Good so far.
    You are missing/skipping/forgetting the cation concentrations.
    The system(s) will eventually reach equilibrium.
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