By Luc Braybury – Updated August 30, 2022

A net ionic equation captures only the ions that actually participate in a chemical reaction, omitting the unchanged “spectator” ions. It is most useful for reactions occurring in aqueous solution, where strong electrolytes fully dissociate into ions and conduct electricity, whereas weak electrolytes or non‑electrolytes contribute minimally to the ionic content.

Step 1 – Write the full balanced equation

Start with the complete reaction. For example:

CaCl₂(aq) + 2AgNO₃(aq) → Ca(NO₃)₂(aq) + 2AgCl(s)

Step 2 – Convert to the total ionic equation

Represent each strong electrolyte as its constituent ions. Weak electrolytes remain as whole molecules.

Ca²⁺ + 2Cl^– + 2Ag⁺ + 2NO₃^– → Ca²⁺ + 2NO₃^– + 2AgCl(s)

Step 3 – Remove the spectator ions to obtain the net ionic equation

Identify ions that appear unchanged on both sides of the equation. Here, Ca²⁺ and NO₃^– are spectators.

2Cl^–(aq) + 2Ag⁺(aq) → 2AgCl(s)