Final answer:
The equation NO2 (aq) + Cr2O72- (aq) => Cr3+ (aq) + NO3- (aq) in acidic solution is balanced as 3 NO2(aq) + Cr2O72- (aq) + 8 H+ (aq) => 3 NO3- (aq) + 2 Cr3+ (aq) + 4 H2O(l).
Step-by-step explanation:
To complete and balance the given chemical equation NO2 (aq) + Cr2O72-(aq) → Cr3+(aq) + NO3-(aq) in acidic solution, we need to follow the steps of balancing redox reactions. This involves balancing the atoms other than hydrogen and oxygen, then balancing the oxygen atoms by adding water molecules (H2O), and then balancing the hydrogen atoms by adding hydrogen ions (H+). Finally, we balance the charge by adding electrons, e-.
Upon following these steps and assuming a balanced reaction under acidic conditions, the balanced net ionic equation is:
3 NO2(aq) + Cr2O72-(aq) + 8 H+(aq) → 3 NO3-(aq) + 2 Cr3+(aq) + 4 H2O(l)
The balanced equation reflects the conservation of mass and charge, with chromium being reduced from Cr2O72- to Cr3+ and nitrogen being oxidized from NO2- to NO3-.