In the following redox reaction: 2Cr(OH)3 + 3OCl− + 4OH− → 2CrO4^{2−} + 3Cl− + 5H2O, which substance acts as the reducing agent?

• A. Cr(OH)3
• B. OH−
• C. OCl−
• D. Cl−

Answer: (A)

Verified step by step guidance

1. Identify the oxidation states of chromium in the reactant Cr(OH)3 and in the product CrO4^{2−}. This will help determine if chromium is oxidized or reduced.
2. Determine the change in oxidation state of chromium from Cr(OH)3 to CrO4^{2−}. An increase in oxidation state indicates oxidation (loss of electrons).
3. Identify the species that is reduced by checking the oxidation states of chlorine in OCl^{-} and Cl^{-}. A decrease in oxidation state indicates reduction (gain of electrons).
4. Recall that the reducing agent is the species that gets oxidized (loses electrons), and the oxidizing agent is the species that gets reduced (gains electrons).
5. Based on the changes in oxidation states, conclude which substance acts as the reducing agent by identifying the species that undergoes oxidation.