How to Balance Net Ionic Equations

We write net ionic equations to understand what is changing in a chemical reaction. Net ionic equations tell us what actually reacted and what we can ignore (called spectator ions). To be successful, you need to understand how to:

• balance molecular equations by changing the coefficients.
• find the charge on ions (both monatomic and polyatomic).
• determine if compounds are soluble and will dissociate in water.

To balance net ionic equations we follow these general rules:

1. Write the balanced molecular equation.
2. Write the state (s, l, g, aq) for each substance.
3. Split strong electrolytes into ions (the complete ionic equation).
4. Cross out the spectator ions on both sides of complete ionic equation.
5. Write the remaining substances as the net ionic equation.

Note: charges in a net ionic equation are conserved. This means that the overall charge (called the net charge) on the reactants side (left) of the equation must equal to the net charge on the products side (right).

Video: How to Balance Net Ionic Equations

Worked examples of Net Ionic Equations

• AgNO₃ + K₂CrO₄ (example of a double displacement net ionic)
• Na₂CO₃ + CuSO₄ (another double displacement reaction)
• HNO₃ + NaOH (Strong Base and Strong Acid)
• NaOH + CH₃COOH (Strong Base and Weak Acid)
• Na₂CO₃ + AgNO₃ (another double displacement reaction)
• NaOH + H₂SO₄ (Strong Base and Strong Acid)