Final Answer:
1. The bases are:
- Assign oxidation numbers to all atoms.
- Identify which atoms change oxidation number (oxidation and reduction).
- Make the total increase in oxidation number equal to the total decrease (i.e., electrons lost = electrons gained).
- Use coefficients to balance atoms and charge, starting with redox-active elements, then others (H, O last), and finally H⁺/OH⁻/H₂O depending on acidic/basic medium.
2. Balanced equations:
I. Fe₂O₃ + 2Al → Al₂O₃ + 2Fe
II. Cu + 4HNO₃ → Cu(NO₃)₂ + 2NO₂ + 2H₂O
III. MnO₂ + 4HCl → MnCl₂ + Cl₂ + 2H₂O
IV. Zn + 2HCl → ZnCl₂ + H₂
V. 6Fe²⁺ + Cr₂O₇²⁻ + 14H⁺ → 6Fe³⁺ + 2Cr³⁺ + 7H₂O
VI. K₂Cr₂O₇ + 14HCl → 2KCl + 2CrCl₃ + 3Cl₂ + 7H₂O
VII. 2Cr(OH)₃ + IO₃⁻ + 4OH⁻ → 2CrO₄²⁻ + I⁻ + 5H₂O
Parent Tip: Review the logic above to help your child master the concept of oxidation reduction reactions worksheet.
