In the Cathode Half Cell, what happens to the solution when current flows in?

In the Cathode Half Cell, what happens to the solution when current flows in?

• A. A buildup of positive charge occurs in the solution
• B. A buildup of negative charge occurs in the solution
• C. The solution remains neutral
• D. The electrode dissolves

Answer: (B)

When current flows into the cathode, electrons arrive at the electrode to drive reduction at that surface. As cations in the adjacent solution are reduced and removed from the solution, positive charge is depleted locally near the cathode. The electrode itself becomes negatively charged due to the incoming electrons, and to balance this charge in the surrounding region, the solution near the cathode acquires a relative excess of negative charge. This creates a small local buildup of negative charge in the solution adjacent to the cathode, while the bulk solution remains overall neutral. The other possibilities don’t fit because they either imply the opposite charge buildup, no local charge separation, or dissolution of the electrode, which isn’t implied by the act of current flow through the cathode half-cell.

When current flows into the cathode, electrons arrive at the electrode to drive reduction at that surface. As cations in the adjacent solution are reduced and removed from the solution, positive charge is depleted locally near the cathode. The electrode itself becomes negatively charged due to the incoming electrons, and to balance this charge in the surrounding region, the solution near the cathode acquires a relative excess of negative charge. This creates a small local buildup of negative charge in the solution adjacent to the cathode, while the bulk solution remains overall neutral. The other possibilities don’t fit because they either imply the opposite charge buildup, no local charge separation, or dissolution of the electrode, which isn’t implied by the act of current flow through the cathode half-cell.