In the redox reaction 6 Fe²⁺ + Cr₂O₇²⁻ + 14 H⁺ → 2 Cr³⁺ + 6 Fe³⁺ + 7 H₂O, what is the reducing agent? A) Fe²⁺ B) Cr₂O₇²⁻ C) H⁺ D) Cr³⁺ E) Fe³⁺

Answer 1

The reducing AGENT is the one being oxidized. If it is being oxidized, it is losing electrons and so the oxidation number will increase.

6 Fe²⁺ + Cr₂O₇²⁻ + 14 H⁺ → 2 Cr³⁺ + 6 Fe³⁺ + 7 H₂O

..+2.......+6...-2........+1.........+3.........+3................oxidation numbers

Fe goes from +2 to +3 and Cr goes from +6 to +3, so which one lost electrons and had the oxidation number increase? It would be Fe (as Fe²⁺)