Question

This reaction takes place in acid. Balance oxygen using H₂O for these half-reactions:

Cr₂O₇⁻² + 6e⁻ = 2Cr⁺³
C₂O₄⁻² = 2CO₂ + 2e⁻

Answer 1

Balancing oxygen in redox half-reactions in an acidic solution involves adding water molecules to balance oxygen atoms and hydrogen ions to balance hydrogen atoms, ensuring both mass and charge are conserved.

Step-by-step explanation:

The question is regarding the balancing of oxygen atoms in redox half-reactions that take place in an acidic solution. For the reduction half-reaction, Cr2O72- + 6e- = 2Cr3+, and for the oxidation half-reaction, C2O42- = 2CO2 + 2e-, water molecules (H2O) are used to balance oxygen atoms, and hydrogen ions (H+) to balance hydrogen atoms in an acidic medium.

To balance the reduction half-reaction: 6e- + 14H+ (aq) + Cr2O72- (aq) → 2Cr3+ (aq) + 7H2O (l). This ensures that the oxygen and hydrogen atoms are balanced, as well as the total charge. The oxidation half-reaction is balanced as is and does not require additional H2O or H+ for the oxygens to balance.