net ionic equation
Summary
A net ionic equation shows only the species that actually change in a solution reaction, after removing spectator ions that appear unchanged on both sides. Aqueous strong electrolytes are written as ions; solids, gases, and weak electrolytes usually stay as formulas. Atoms and charge must both balance.
Detail
Meaning: A net ionic equation shows only the species that actually change in a reaction in solution. Write the balanced equation, split every aqueous strong electrolyte (soluble salts, strong acids, strong bases) into ions, then cancel ions that appear unchanged on both sides. Those are spectator ions. Solids, gases, liquids such as H₂O, and weak acids or bases stay as whole formulas. Example: AgNO₃(aq) + NaCl(aq) → AgCl(s) + NaNO₃(aq) reduces to Ag⁺(aq) + Cl⁻(aq) → AgCl(s), with Na⁺ and NO₃⁻ as spectators.
On the MCAT: Expect passages on precipitation, solubility, Ksp, and titrations. Typical questions ask which ion is a spectator, which net reaction occurs when two solutions are mixed, or what a strong acid and strong base neutralization reduces to (H⁺ + OH⁻ → H₂O). Check that atoms and total charge both balance; charge conservation is a quick way to eliminate wrong answer choices.
Common confusion: Students split everything into ions, including precipitates and weak electrolytes. Typically only dissolved strong electrolytes are written as ions; CH₃COOH(aq) and NH₃(aq) stay intact, and AgCl(s) is not split. Also, spectator ions are still present in the solution. They just do not take part in the change.
Sources
- Chemistry: The Central Science
- General Chemistry: Principles and Modern Applications
- Chemistry (Zumdahl)
Written for the MCAT and checked before it was published. For study reference only. Spotted an error? Let us know.