Mistake Master

Net Ionic Equations

▶︎  Watch it animatedinteractive step-through · ~3 min · optional

A net ionic equation shows only the species that actually change in a reaction. Start from the molecular equation, split the strong electrolytes into their ions (the complete ionic equation), then cancel the spectator ions — the ones that appear unchanged on both sides. Solids, weak acids, and gases stay together, undissociated.

UNIT 4 TOPIC 4.2 • NET IONIC EQUATIONS SPECTATOR STRIPPER START WITH THE MOLECULAR EQUATION AgNO₃(aq) + NaCl(aq) → AgCl(s) + NaNO₃(aq) Balanced molecular equation — formulas stay intact here. 1. DISSOCIATE ELECTROLYTES Complete ionic equation AgNO₃(aq) + NaCl(aq) → Ag⁺(aq) + NO₃⁻(aq) + Na⁺(aq) + Cl⁻(aq) → AgCl(s) + Na⁺(aq) + NO₃⁻(aq) Aqueous strong electrolytes split into ions. The AgCl(s) precipitate stays together as a solid. 2. CANCEL SPECTATOR IONS Spectators cancel Na⁺(aq) and NO₃⁻(aq) They appear unchanged on both sides — not in the solid. Na⁺ NO₃⁻ spectator ions removed 3. WRITE THE NET IONIC EQUATION Ag⁺(aq) + Cl⁻(aq) AgCl(s) white solid precipitate Ag⁺ Cl⁻ Cl⁻ Ag⁺ CONSERVATION CHECK Atoms and charge must balance in every form. Net charge: 0 → 0 Never cancel solids, liquids, gases, or weak electrolytes. AP Chemistry · Unit 4 · Chemical Reactions
From molecular to net ionic. Write the balanced molecular equation, dissociate the strong electrolytes into ions (complete ionic equation), then cancel the spectator ions that appear unchanged on both sides. What remains is the net ionic equation.
Spectator Stripper · Open the sandbox →

The mistakes cluster around what to split and what to cancel: only strong, soluble electrolytes dissociate (not solids or weak acids), and only truly identical ions cancel. Getting the dissociation and cancellation rules right is what makes a net ionic equation correct.

The work

3 ways in · any order
Lesson
Net Ionic Equations

Net ionic equations keep only the species that change, after dissociating strong electrolytes and canceling spectators. The lesson works the three-equation sequence, then closes with a ten-scenario check.

Skill check · 10 scenarios
Diagnostic
10-item topic check

Ten items spanning the Topic 4.2 misconceptions: assuming a partner swap always reacts, splitting a solid product or a weak acid, misjudging solubility, and canceling ions that are not identical.

Not started · 10 items · ~15 min
Targeted Practice
Drill a single misconception

Pick one of the failure modes you missed and drill it on its own. The round is adaptive: two correct in a row clears the misconception and moves you to the next.

Take the diagnostic to identify your misconceptions