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Ionic Equations Metathesis and displacement reactions, especially those occurring in aqueous solutions (which is most of them), can be better understood using the ideas of spectator ions and net ionic equations. Consider a typical acid-base reaction: Recognizing that this is really a reaction involving dissolved ions, we can rewrite this as a full ionic equation. Note that Na+ and Cl- don't really do anything. They are the same on the right hand side as they are on the left hand side. They watch but do not participate and we therefore call them spectator ions. In a net ionic equation we eliminate the spectator ions: This net ionic reaction is special. It represents the net ionic equation for any acid-base neutralization reaction, and vividly illustrates the role of the formation of a nonelectrolyte as a driving force in these kind of reactions. Note how the nonionic water molecule has, in effect, scavenged the hydrogen and hydroxide ions that formed it, rendering them unavailable for any further participation in ionic reactions.

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