What net ionic equation do I get?

How it works

1. Balance. The page reads each formula (brackets, charges written Fe^3+ or SO4^2-, optional states) and finds the smallest whole-number coefficients that make every element and the total charge equal on both sides: the null space of the element-count matrix, by exact row reduction. An equation with no balance, or more than one independent balance, has no answer.

2. Split strong electrolytes. For each formula, times its coefficient:

• An ion you type (with a charge) stays as that ion, in solution (aq).
• A strong acid (HCl, HBr, HI, HNO₃, HClO₄, H₂SO₄; OpenStax Table 4.2) gives H⁺(aq) and its anion; H₂SO₄ gives 2H⁺ + SO₄²⁻.
• An ionic compound is a formula with one metal (or NH₄⁺ groups) and one anion from this list: Cl⁻, Br⁻, I⁻, F⁻, S²⁻, OH⁻, NO₃⁻, ClO₃⁻, ClO₄⁻, HCO₃⁻, C₂H₃O₂⁻ (acetate, in any atom order), SO₄²⁻, CO₃²⁻, CrO₄²⁻, PO₄³⁻. The metal’s charge is the anion charge divided by the number of metal atoms, and must be one it commonly takes: 1 for Li, Na, K, Rb, Cs, Ag; 2 for Be, Mg, Ca, Sr, Ba, Zn, Cd, Ni, Mn, Pb, Sn; 3 for Al and Cr; 2 or 3 for Fe and Co; 1 or 2 for Cu; Hg as Hg²⁺ or as the pair Hg₂²⁺. A soluble one gives its cations and anions (aq); an insoluble one stays as the solid (s).
• Everything else (water, gases, weak acids, oxides, metals and other molecules) stays whole. With no state typed, water is shown as H₂O(l) and the others with no state.
• A typed state wins: (aq) splits an ionic compound or strong acid; (s), (l) or (g) keeps it whole.

Solubility (OpenStax Table 4.1), checked in this order:

1. Compounds of NH₄⁺, Li⁺, Na⁺, K⁺, Rb⁺, Cs⁺: soluble.
2. Acetates, hydrogen carbonates, nitrates, chlorates: soluble.
3. Chlorides, bromides, iodides: soluble except with Ag⁺, Hg₂²⁺, Pb²⁺.
4. Fluorides: soluble except with group 2 cations, Pb²⁺, Fe³⁺.
5. Sulfates: soluble except with Ag⁺, Ba²⁺, Ca²⁺, Hg₂²⁺, Pb²⁺, Sr²⁺.
6. Carbonates, chromates, phosphates, sulfides: insoluble (rule 1 covers their exceptions).
7. Hydroxides: insoluble except with Ba²⁺ (rule 1 covers group 1).
8. Any other pair (a perchlorate of a metal outside group 1): no answer unless you type its state.

3. Cancel spectators. The complete ionic equation adds equal terms on each side (ions by formula and state). Each term on both sides is reduced by the smaller count; ions removed this way are listed as spectators. If one side is left empty, every ion is a spectator and there is no answer (no reaction). The rest is divided by the greatest common divisor of its coefficients.

Output format. Terms keep the order in which they first appear in the complete ionic equation; a coefficient of 1 is not written; subscripts and charges are printed as Unicode subscripts and superscripts.

Worked examples by hand

NaCl(aq) + AgNO₃(aq) = AgCl(s) + NaNO₃(aq) (OpenStax). Balanced as written. Complete: Na⁺ + Cl⁻ + Ag⁺ + NO₃⁻ → AgCl(s) + Na⁺ + NO₃⁻. Spectators Na⁺(aq), NO₃⁻(aq). Net: Cl⁻(aq) + Ag⁺(aq) → AgCl(s).

Ba(OH)₂ + HNO₃ = Ba(NO₃)₂ + H₂O (OpenStax Example 4.4). Balanced: Ba(OH)₂(aq) + 2HNO₃(aq) → Ba(NO₃)₂(aq) + 2H₂O(l). Complete: Ba²⁺ + 2OH⁻ + 2H⁺ + 2NO₃⁻ → Ba²⁺ + 2NO₃⁻ + 2H₂O(l). Cancelling Ba²⁺ and NO₃⁻ leaves 2OH⁻ + 2H⁺ → 2H₂O; dividing by 2: OH⁻(aq) + H⁺(aq) → H₂O(l).

CaCl₂ + Na₃PO₄ = Ca₃(PO₄)₂ + NaCl. Balanced: 3CaCl₂(aq) + 2Na₃PO₄(aq) → Ca₃(PO₄)₂(s) + 6NaCl(aq) (phosphates are insoluble except with group 1). Spectators Cl⁻(aq), Na⁺(aq). Net: 3Ca²⁺(aq) + 2PO₄³⁻(aq) → Ca₃(PO₄)₂(s).

HC₂H₃O₂ + NaOH = NaC₂H₃O₂ + H₂O. Acetic acid is weak and stays whole; NaOH and sodium acetate are soluble. Spectator Na⁺(aq). Net: HC₂H₃O₂ + OH⁻(aq) → C₂H₃O₂⁻(aq) + H₂O(l).