During the electrolysis of molten KBr, which species are produced at the anode and cathode, respectively?

• A. K at the anode, Br2 at the cathode
• B. O2 at the anode, H2 at the cathode
• C. Br2 at the anode, K at the cathode
• D. KBr at both electrodes

Answer: (C)

Verified step by step guidance

1. Identify the ions present in molten KBr. Since it is molten, it dissociates into K⁺ (potassium ions) and Br⁻ (bromide ions).
2. Determine what happens at the cathode (the negative electrode). Cations (positive ions) move toward the cathode to gain electrons (reduction). Here, K⁺ ions will gain electrons to form potassium metal (K). The half-reaction is: \(\mathrm{K^{+} + e^{-} \rightarrow K}\).
3. Determine what happens at the anode (the positive electrode). Anions (negative ions) move toward the anode to lose electrons (oxidation). Here, Br⁻ ions will lose electrons to form bromine gas (Br₂). The half-reaction is: \(\mathrm{2Br^{-} \rightarrow Br_{2} + 2e^{-}}\).
4. Confirm that no other species such as O₂ or H₂ are produced because the electrolysis is of molten KBr, not an aqueous solution, so water is not involved.
5. Summarize the products: bromine gas (Br₂) is produced at the anode, and potassium metal (K) is produced at the cathode.