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What does this symbol mean in a chemical equation?

  1. Apr 3, 2016 #1
    I recently stumbled across a chemical equation, which had a symbol I have never seen before.
    If anyone can tell me what this symbol means, I would be very grateful.

    Here's the equation:
    Ca(OH)2(aq) + Na2CO3(s) → CaCO3 ↓ + 2 NaOH(aq)

    ...and I'd like to know what the "↓" symbol means.

    Many thanks in advance.
  2. jcsd
  3. Apr 3, 2016 #2


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    Staff: Mentor

    It means that CaCO3 precipitates and is not in solution.
  4. Apr 3, 2016 #3


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    Staff: Mentor

    Just like ↑ in

    CaCO3 + 2HCl → CO2↑ + CaCl2 + H2O

    means evolving gas.

    Note that is the reagent states are given (as (g), (aq), (s)) these arrows are typically redundant.
  5. Apr 3, 2016 #4
    Ahh! That does make sense.

    So that would mean that this reaction could be used to produce just NaOH if the CaCO3 was removed (which the arrow states would be possible because the CaCO3 is not chemically bonded in any way with the NaOH, and could therefore be removed.)

    Thanks a lot!
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