Final answer:
Complete ionic equations show the complete reaction including all ions and compounds in their hydrated and dissociated forms in solution.
Step-by-step explanation:
Complete ionic equations are equations that show the complete reaction including all ions and compounds. They depict what is happening in a reaction on the ionic level and are especially useful for reactions involving electrolytes in aqueous solutions. In a complete ionic equation, ionic compounds that dissolve separate into individual ions, and are written as dissociated ions in the equation.
For instance, the reaction between hydrochloric acid (HCl) and sodium hydroxide (NaOH) as a molecular equation would simply show the reactants and products as undissociated compounds. Turning this into a complete ionic equation, however, would involve showing all the substances in their ionic forms, as follows:
H+ (aq) + Cl(aq) + Na+ (aq) + OH (aq) → H₂O(l) + Na+ (aq) + Cl (aq)
This equation shows every ion separate and hydrated, as they are present in the water phase. Notice that the water is written as a molecule (H₂O) since it exists as a molecule and not as ions in the reaction. The complete ionic equation differs from the net ionic equation, which is derived by omitting all spectator ions that do not participate in the reaction and appear on both sides of the complete ionic equation with the same coefficients.