Here's how to write the ionic equation for the reaction of hydrochloric acid (HCl) and sodium hydroxide (NaOH):

1. Write the balanced molecular equation:

HCl(aq) + NaOH(aq) → NaCl(aq) + H₂O(l)

2. Break down the soluble ionic compounds into their ions:

H⁺(aq) + Cl⁻(aq) + Na⁺(aq) + OH⁻(aq) → Na⁺(aq) + Cl⁻(aq) + H₂O(l)

3. Cancel out the spectator ions (ions that appear on both sides of the equation):

H⁺(aq) + OH⁻(aq) → H₂O(l)

This is the complete ionic equation.

The net ionic equation:

The net ionic equation focuses only on the species directly involved in the reaction. Since water is a liquid and doesn't break down into ions, the net ionic equation is the same as the complete ionic equation:

H⁺(aq) + OH⁻(aq) → H₂O(l)