Final answer:
To balance the redox equation Cr2O72– + NO → Cr3+ + NO3–, one must write the separate oxidation and reduction half-reactions, balance atoms and charges in each, ensure electrons are equal and opposite, and then combine and simplify the equation.
Step-by-step explanation:
Steps to Balance the Redox Equation
To answer the question on how to balance the redox equation Cr2O72– + NO → Cr3+ + NO3– using half-reactions, we must apply the steps for balancing redox reactions in an aqueous solution. First, we write the oxidation and reduction half-reactions. In this case, Cr2O72– is reduced to Cr3+ and NO is oxidized to NO3–.
For the reduction half-reaction (Cr2O72– to Cr3+), we balance the oxygen by adding water molecules and the hydrogen by adding H+ ions (in acidic solution), then balance the charge by adding electrons. For the oxidation half-reaction (NO to NO3–), we balance the oxygen by adding water, the hydrogen by adding H+ ions, and finally, the charge by adding or removing electrons.
This process requires the balancing of atoms and charges in each half-reaction separately, and once that is done, we combine the two half-reactions and ensure that the electrons lost in oxidation equal the electrons gained in reduction. Finally, we simplify the equation by canceling out species that appear on both sides.