How do I balance the equation for the oxidation of diphenylcarbazide by Cr⁶⁺ to give diphenylcarbazone and Cr³⁺?
1 Answer
Dec 4, 2014
The easiest way is to use the ion electron method.
Explanation:
Here are the steps.
Net ionic equation
Cr₂O₇²⁻ + C₆H₅NHNHCONH-NHC₆H₅ → Cr³⁺ + C₆H₅NHNHCON=NC₆H₅
Skeleton half–reactions
Cr₂O₇²⁻ → Cr³⁺
C₆H₅NHNHCONH-NHC₆H₅ → C₆H₅NHNHCON=NC₆H₅
Balanced half-reactions
Cr₂O₇²⁻ + 14H⁺ + 6e⁻ → 2Cr³⁺ + 7H₂O
C₆H₅NHNHCONH-NHC₆H₅ → C₆H₅NHNHCON=NC₆H₅ + 2H⁺ + 2e⁻
Equalize electrons transferred
1 × [Cr₂O₇²⁻ + 14H⁺ + 6e⁻ → 2Cr³⁺ + 7H₂O]
3 × [C₆H₅NHNHCONH-NHC₆H₅ → C₆H₅NHNHCON=NC₆H₅ + 2H⁺ + 2e⁻]
Add half-reactions
Cr₂O₇²⁻ + 3C₆H₅NHNHCONH-NHC₆H₅ + 8H⁺ → 2Cr³⁺ + 3C₆H₅NHNHCON=NC₆H₅ + 7H₂O
Add spectator ions
K₂Cr₂O₇ + 3C₆H₅NHNHCONH-NHC₆H₅ + 4H₂SO₄ → Cr₂(SO₄)₃ + 3C₆H₅NHNHCON=NC₆H₅ + K₂SO₄ + 7H₂O
