Net ionic equation for reactions

Question

When aqueous solutions of cobalt (II) sulfate and potassium phosphate are combined, solid cobalt (II) phosphate and a solution of potassium sulfate are formed. What is the net ionic equation for this reaction?

Answer 1

When you have a precipitate formed (s), the net ionic is the two ions forming the precipitate. In this case it will be Co²⁺ and PO₄^3-. It would be 3Co²⁺(aq) + 2PO₄^3-(aq) ==> Co₃(PO₄)₂(s)

Let's look at this in more detail

The complete molecular equation is 3CoSO₄(aq) + 2K₃PO₄(aq) ==> 3K₂SO₄(aq) + Co₃(PO₄)₂(s)

Ionic equation is: 3Co²+(aq) + 3SO₄^2-(aq) + 6K⁺(aq) + 2PO₄^3-(aq) => 6K⁺(aq) + 3SO₄²-(aq) + Co₃(PO₄)₂(s)

Net ionic after removing spectator ions (those in italics): 3Co²⁺(aq) + 2PO₄^3-(aq) ==> Co₃(PO₄)₂(s)