What is produced at the cathode during the electrolysis of aqueous NaI?

• A. Sodium metal (Na)
• B. Oxygen gas (O2)
• C. Iodine (I2)
• D. Hydrogen gas (H2)

Answer: (D)

Verified step by step guidance

1. Identify the components present in the aqueous solution: Na⁺, I⁻, H₂O.
2. Determine the possible reactions at the cathode. In aqueous solutions, water can be reduced to form hydrogen gas (H₂), and Na⁺ can be reduced to form sodium metal (Na).
3. Compare the standard reduction potentials for the possible cathode reactions: Na⁺ + e⁻ → Na and 2H₂O + 2e⁻ → H₂ + 2OH⁻.
4. Recognize that the reduction of water to hydrogen gas has a more favorable (less negative) reduction potential than the reduction of Na⁺ to Na.
5. Conclude that hydrogen gas (H₂) is produced at the cathode because it is thermodynamically more favorable than the production of sodium metal in aqueous solution.