What is the net ionic equation for the precipitation of iron(II) oxalate dihydrate when oxalic acid is added to a solution of iron(II) ions?

The net ionic equation for the precipitation of iron(II) oxalate dihydrate can be derived from the overall reaction that occurs when oxalic acid is introduced to a solution containing iron(II) ions. The relevant species in the solution include iron(II) ions (Fe²⁺), oxalate ions (C₂O₄^2-), and water.

First, we consider the dissociation of oxalic acid (H₂C₂O₄) in the solution into hydrogen ions (H⁺) and oxalate ions:

H₂C₂O₄ ⇌ 2 H⁺ + C₂O₄^2-

Next, we write the reaction where iron(II) ions combine with oxalate ions to form insoluble iron(II) oxalate dihydrate:

Fe²⁺ (aq) + C₂O₄^2- (aq) → FeC₂O₄·2H₂O (s)

Now, when we combine the reactions, we can eliminate the spectator ions (in this case, the hydrogen ions from oxalic acid) to arrive at the net ionic equation:

Net Ionic Equation:

Fe²⁺ (aq) + C₂O₄^2- (aq) → FeC₂O₄·2H₂O (s)

This equation shows the formation of the solid precipitate of iron(II) oxalate dihydrate from its ions in solution. The phases indicate that both reactants are aqueous (dissolved in water) and the product is a solid precipitate.