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Predicting precipitates in a solution

  1. Mar 11, 2017 #1
    Let's say we have a solution supersaturated with several species of ions, and there are a few potential precipitates predicted to be formed that all have one contain one species in common (therefore they are competing for that common ionic species). How can we predict which species will precipitate, assuming that the common species is not in excess?
  2. jcsd
  3. Mar 11, 2017 #2
    Electronegativity difference perhaps? Sakto ba? Pagtawas oi.?:)

    This is a topic on chemical kinetics. Rate of reaction.
  4. Mar 11, 2017 #3
    I can't afford it :cry:

    Well I was thinking maybe this may be more related to the thermodynamic properties of the predicted precipitates or their formation. Although electronegativity might play a role, I worry that an analysis through that framework might get too complicated since it is in the atomic scale.

    As for a reaction kinetics approach, I worry it might not provide us information on which precipitate is favored to form.
  5. Mar 11, 2017 #4
    May be isolating one over the other specie (1 to 1) might help you somehow to analyse the problem at a fixed temperature. Does temperature change during the mixing of constituents?

    I don't know, if its an experiment your doing, you have no worries at all. As nature dictates what's gonna happen. If you are may be verifying or proving a theory in reality, I think it needs a lot to think. Observation wins over set of theories.
  6. Mar 11, 2017 #5


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    Staff: Mentor

    Thermodynamics would tell you what to expect in a long term, kinetics will predict short term outcome - and they don't have to be identical.

    These things are best checked experimentally.
  7. Mar 11, 2017 #6
    It's all theoretical.
  8. Mar 11, 2017 #7
    This is a mere theoretical analysis, actually.

    Basically, the idea is that if I had a solution supersaturated with ions A, B, X, and a variety of other ions; both AX and BX are known to be stable salts, but X is not available in excess, which of the two would be favored to precipitate after the solution reaches equilibrium (long term)? I initially thought that reactivity of the ionic species would dictate which would precipitate, but I read that it only works for single displacement reactions. And for this case, I believe it is a more complex system (or is it?).

    I would appreciate if somebody could assist me with this analysis. Thank you!
  9. Mar 11, 2017 #8
    It would somehow end up to proximity of molecules and foremost opposite ions. Just a mere guess.
  10. Mar 11, 2017 #9
    I believe that would only apply to predicting "short-term" (or instantaneous, even!) products. I am concerned with the equilibrium products (long term), which I assume that all species were allowed to "meet with each other" and eventually "find their best partner," so to speak.

    Nonetheless, I thank you for your input. I appreciate it.
  11. Mar 11, 2017 #10
    If it has to be long term, then it's a factor of gravity, heavy molecules settles lighter ones float.:cry: mao ba kabs?
  12. Mar 11, 2017 #11
    Na hala, sige kabs puwede na ni. Pasar na lagi ka :wink:
  13. Mar 11, 2017 #12
    So nice to find you here:smile:.-msu-iit
  14. Mar 11, 2017 #13


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    Staff: Mentor

    You are not asking about which one will precipitate, but about which one is the stable, final form, these are slightly different things.

    For that comparing Ksp should be perfectly enough (as it stems from thermodynamics).
  15. Mar 11, 2017 #14
    I see, thank you for the correction. I will take a look at the problem considering Ksp. This definitely makes sense. Thank you, I really appreciate your help!

    Have a good day!
  16. Mar 11, 2017 #15
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