Standard potentials say oxygen should form at the anode when aqueous sodium chloride is electrolyzed, yet chlorine appears. What explains it?

1. Two oxidations compete at the anode, water going to oxygen and chloride going to chlorine. 2. On standard potentials alone, oxidizing water needs the smaller push, so oxygen looks favored. 3. In practice the extra voltage needed beyond the theoretical value is the overpotential. 4. The overpotential for oxygen is unusually large. 5. That extra cost makes the oxygen route more expensive than it looks on paper. 6. Chlorine gas is therefore what actually forms at the anode. 7. Saying water cannot be oxidized is false, since it is oxidized during the electrolysis of pure water. 8. Sodium ions migrate to the cathode, not the anode, so they cannot block the anode surface. _Source: OpenStax Chemistry (CC BY 4.0), Chs 7 and 17, section 17.7 Electrolysis_