During electrolysis, where do negative ions collect?

• A. At the cathode
• B. At the anode
• C. In the electrolyte near the cathode
• D. In the electrode

Answer: (B)

During electrolysis, ions respond to the electric field set up by the power supply. Negatively charged ions (anions) are attracted to the positive electrode, the anode. When they reach the surface of the anode, they lose electrons in a discharge reaction (oxidation). So negative ions collect at the anode.

The cathode, being the negative electrode, attracts positive ions (cations) which gain electrons there. The electrolyte near the cathode isn’t where negative ions accumulate, and ions don’t generally collect inside the solid electrode unless a specific deposition reaction occurs at its surface.