- The ion-electron method is based on separating the redox reaction into two half-reactions: oxidation and reduction. Each half-reaction is balanced separately for atoms and charge by adding electrons, H⁺ (in acidic medium), OH⁻ (in basic medium), and H₂O as needed. The number of electrons lost in oxidation must equal the number gained in reduction, so the half-reactions are multiplied by appropriate coefficients before combining them to give the overall balanced equation.
I. Fe₂O₃ + 2Al → Al₂O₃ + 2Fe
Balanced as written (already balanced).
II. Cu + 4HNO₃ → Cu(NO₃)₂ + 2NO₂ + 2H₂O
Balanced using ion-electron method in acidic medium.
III. MnO₂ + 4HCl → MnCl₂ + Cl₂ + 2H₂O
Balanced using ion-electron method in acidic medium.
IV. Zn + 2HCl → ZnCl₂ + H₂
Balanced as written (already balanced).
V. 6Fe²⁺ + Cr₂O₇²⁻ + 14H⁺ → 6Fe³⁺ + 2Cr³⁺ + 7H₂O
Balanced using ion-electron method in acidic medium.
VI. K₂Cr₂O₇ + 14HCl → 2KCl + 2CrCl₃ + 3Cl₂ + 7H₂O
Balanced using ion-electron method in acidic medium.
VII. 2Cr(OH)₃ + IO₃⁻ + 4OH⁻ → I⁻ + 2CrO₄²⁻ + 5H₂O
Balanced using ion-electron method in basic medium.
Parent Tip: Review the logic above to help your child master the concept of redox reactions worksheet.
