Here's why:
* Dichromate ion (Cr₂O₇²⁻): The oxidation state of chromium in dichromate is +6.
* Chromium(III) ion (Cr³⁺): This is the common reduced form of chromium when dichromate acts as an oxidizing agent.
The reaction:
In typical reactions, dichromate ions are reduced to chromium(III) ions. For example, in acidic solution:
Cr₂O₇²⁻(aq) + 14H⁺(aq) + 6e⁻ → 2Cr³⁺(aq) + 7H₂O(l)
Here, each chromium atom gains 3 electrons, causing its oxidation state to decrease from +6 to +3.
