Redox Half-Reaction Balancer Coach

Build the balance one decision at a time. Check Answer unlocks each new step only after your work is correct.

1. Separate oxidation (electron loss) from reduction (electron gain). Reactants stay on the left and products stay on the right.
2. Balance elements other than oxygen and hydrogen first. This coach supplies those skeleton coefficients after you split the reaction. Balance O with H₂O, then H with H⁺.
3. Add electrons to balance charge. One electron has charge −1.
4. Multiply whole half-reactions to equalize electrons.
5. Add the half-reactions and cancel species shared by both sides.
6. For basic media, add OH⁻ to both sides to neutralize H⁺, form H₂O, and cancel excess water.

Use Undo for an extra addition. Earlier phases lock once checked. Click a token and its destination instead of dragging; all controls also work with Tab, Enter and Space.