Section: Chemical and Physical Foundations of Biological Systems

22) What is the identity of the reducing agent and oxidizing agent, respectively, in the reaction shown below? 2Cr(OH)₃ + 3H₂O₂ + 4NaOH ? 2Na₂CrO₄ + 8H₂O

1. Cr(OH)₃  and NaOH
2. Cr(OH)₃ and H₂O₂
3. H₂O₂ and Cr(OH)₃
4. H₂O₂ and NaOH

To answer this question, you must identify the atom that is reduced and the atom that is oxidized. In the reaction above, chromium is oxidized from +3 to +6, which makes chromium hydroxide the reducing agent. Alternatively, oxygen in hydrogen peroxide is reduced from -1 to -2, which makes it the oxidizing agent. Thus, the correct answer is B.