To derive the net ionic equation for the reaction of excess copper(II) sulfate (CuSO4) with ammonia (NH3), we first need to recognize the products formed in this reaction.
When CuSO4 is mixed with NH3, a complex ion is formed. The primary reaction occurs when ammonia reacts with copper(II) ions (Cu2+). The overall reaction can be represented as:
CuSO4 + 4 NH3 → [Cu(NH3)4]SO4
In this equation, the ammonia ligands form a complex with the copper ions, while the sulfate ions (SO42-) remain as spectator ions in solution.
Next, we write the complete ionic equation, breaking down the soluble salts into their ions:
Cu2+ + SO42- + 4 NH3 → [Cu(NH3)4]SO4
Now, to find the net ionic equation, we eliminate the spectator ions that do not participate directly in the reaction. In this case, the sulfate ions are the spectator ions:
Cu2+ + 4 NH3 → [Cu(NH3)4]2+
Thus, the net ionic equation for the reaction of excess CuSO4 with ammonia is:
Cu2+ + 4 NH3 → [Cu(NH3)4]2+
This equation shows that the copper ions react with four molecules of ammonia to form a complex ion, highlighting the key chemical change in the reaction.