Final answer:
To balance the redox reaction where SO2 is oxidized to SO4 2- and Fe2+ is oxidized, we should use the half-reaction method in basic solution, carefully balancing atoms, charges, and adding water (H2O) and hydroxide (OH-) as needed to ensure both mass and charge balance.
Step-by-step explanation:
To balance the redox reaction where SO2 is oxidized to SO42- and Fe2+ is oxidized, we will balance it in basic solution using the half-reaction method.
We start by writing the two half-reactions for oxidation and reduction.
Oxidation half-reaction (Sulfur oxidation):
SO2 → SO42-
Reduction half-reaction (Iron oxidation):
Fe2+ → Fe3+
Next, we balance the atoms other than O and H. After that, we balance the oxygen atoms by adding H2O, then balance the hydrogen atoms by adding OH- ions. Then, we balance the charges by adding electrons.
Finally, we combine the half-reactions ensuring that the electrons are balanced, and make adjustments to balance the overall equation in basic solution. This may include adding additional water molecules or OH- ions to fully balance the reaction.