A molecular equation shows whole-formula reactants and products, but it hides what's actually happening in solution: strong electrolytes are dissolved as separate ions, not intact molecules. This calculator dissociates every strong electrolyte, cancels the ions that don't participate in the reaction, and shows you the net ionic equation — the version that reflects what's really reacting.
How the Net Ionic Equation Calculator works
Starting from your balanced molecular equation, the calculator checks each formula's phase label. Anything marked (aq) is tested against a recognized set of strong electrolytes — soluble ionic salts, strong acids, and strong bases — using standard solubility rules to decide which salts actually dissolve. A recognized strong electrolyte splits into its cation and anion, each carrying the original formula's coefficient; everything else (solids, liquids, gases, weak acids, weak bases, and molecular compounds) is left as a whole formula. That expanded equation is the complete ionic equation.
From there, the calculator looks for any ion that appears with the exact same formula, charge, and coefficient on both the reactant and product side. Those are spectator ions — present before and after the reaction, unchanged — and removing them from both sides leaves the net ionic equation.
Inputs and what they mean
Balanced molecular equation is the whole-formula equation you'd normally write for the reaction, with a phase label — (aq), (s), (l), or (g) — after every formula. The calculator assumes the equation is already balanced; it doesn't balance coefficients for you.
Missing phase labels controls what happens if you skip a phase label. "Use phases exactly as typed" treats a missing label as an error so you can fix it. "Auto-fill missing phases" instead assigns water to (l), a short list of common gases to (g), and applies solubility rules to the rest to guess (aq) vs. (s) — useful for a quick check, but always verify an auto-filled phase against your actual reaction conditions.
Limits and edge cases
The ion tables and solubility rules here cover the compounds that show up in a standard general-chemistry course — common metal cations, polyatomic ions, and the textbook solubility-rule exceptions. Less common ions, coordination complexes, and organic acids beyond the handful of curated weak acids may not be recognized; when that happens, the calculator leaves the formula intact rather than guessing at a split, which is the safer failure mode. It also doesn't balance unbalanced equations or verify that your reaction is chemically valid — it only dissociates, applies solubility rules, and cancels spectators from what you enter.