[AFT]

my question is what "arrow" should i use to indicate the precipitation reactions... i know in earlier grades, it was represented by the single arrow (-->) but as we were introduced to the 'equilibrium double arrow ( <--> )', i was wondering if it would be appropriate to use that instead of the single arrow..?

ie.  Ba(NO₃)_{2 (aq)} + Na₂SO_{4 (aq)}  "arrow"  BaSO_{4 (s)} + 2NaNO_{3 (aq)}   //    Net Ionic: Ba²⁺_(aq) + SO₄^2-_(aq)  "arrow"  BaSO_{4 (s)}

is it a single arrow (-->) or equilibrium double arrow ( <--> ) and why?


Also, could someone confirm this equation:
(are the phase labels, reaction arrow and balancing correct?)

BaCO_{3 (s)} + 2HNO_{3 (aq)}   <-->   Ba(NO₃)_{2 (aq)} + H₂CO_{3 (aq)}    //    Net Ionic: BaCO_{3 (s)}  <-->  Ba²⁺_(aq) + CO₃^2-_(aq)

Thanks!!!

[oceane]

1st part:
You would use the single arrow because the barium sulphate precipitating out of the solution drives the equilibrium to the side of the products.  Had both the products and reactants been in solution, there would be the possibility of an equilibrium.

[Yggdrasil]

For the first part, a double arrow is appropriate because solubility is an equilibrium between solid and liquid.  You should use single arrows if the products are removed from solution (e.g. a gas bubbling out of a solution) or if the reverse reaction is immeasurably slow compared to the rate of the forward reaction (e.g. H₂ + O₂ --> H₂O)