Write the balanced net ionic equation for the precipitation of manganese(II) hydroxide from aqueous solution

Answer 1

Since you don't specify what the reactants are, I'll make some up. How about manganese sulfate and potassium hydroxide (although it won't matter for the net ionic equation). That would give:

MgSO₄ + 2KOH → Mg(OH)₂ + K₂SO₄

You say this is an aqueous solution and that manganese (II) hydroxide is a precipitate so that makes it:

MgSO₄(aq) + 2KOH(aq) → Mg(OH)₂(ppt) + K₂SO₄(aq)

The Total Ionic Equation would then be:

Mg⁺²(aq) + SO₄^-2(aq) + 2K⁺ + 2OH^-(aq) → Mg(OH)₂(ppt) + 2K⁺ + SO₄^2-(aq)

Notice that there are equal amounts of SO₄^-2(aq) and 2K⁺ (aq) ions on each side of the equation? These are spectator ions. We can eliminate them to get the net ionic equation which then becomes:

Mg⁺²(aq) + 2OH^-(aq) → Mg(OH)₂(ppt)

Answer 2

Mg²⁺_(aq) + 2 OH^-_(aq) → Mg(OH)_2(s)