Question

what is the half-reaction occurring at the anode in this cell?
cr³⁺→cr⁶⁺ + 3e⁻
cr³⁺ + 3e⁻→cr
cr³⁺ + 3e⁻→cr⁶⁺
cr→cr³⁺ + 3e⁻

Explanation:

In an electrolytic cell (indicated by the battery), the anode is where oxidation occurs (loss of electrons). The Cr electrode is at the anode (connected to the positive terminal of the battery). Oxidation involves an atom losing electrons and increasing its oxidation state. Cr (oxidation state 0) is oxidized to \( \text{Cr}^{3+} \) (oxidation state +3), so the half - reaction is \( \text{Cr}
ightarrow \text{Cr}^{3+}+3\text{e}^- \), as this shows the loss of 3 electrons (oxidation) at the anode.

Answer:

D. \( \text{Cr}
ightarrow \text{Cr}^{3+}+3\text{e}^- \)