Ionic equations and spectator ions
Ionic equations are different to symbol equations.
For example, an equation showing hydrochloric acid being neutralised by sodium hydroxide:
\(HCl + NaOH \to NaCl + H_2^{}O\)
The ionic equation for the above process shows the charges involved. State symbols are added and ions in solution \((aq)\)are separated with a \( +\) sign.
\(H_{}^ + (aq) + Cl_{}^ - (aq) + Na_{}^ + (aq) + OH_{}^ - (aq) \to Na_{}^ + (aq) + Cl_{}^ - (aq) + H_2^{}O(l)\)
This can be shortened further by removing the spectator ions. Spectator ions are ions that are present during the reaction but are unchanged by the reaction, and so are present in the same state on both sides of the equation.
Re-writing the equation without the spectator ions gives:
\(H_{}^ + (aq) + OH_{}^ - (aq) \to H_2^{}O(l)\)
This change occurs in every neutralisation reaction.