What is the function of ions in a salt bridge?

The correct function of ions in a salt bridge is to balance charge between the half-cells. In electrochemical cells, oxidation occurs at the anode and reduction at the cathode, leading to an accumulation of positive charge in one half-cell and negative charge in the other. This imbalance can halt the flow of electrons and disrupt the electrochemical reaction.

The ions in the salt bridge, which is typically filled with an electrolyte solution, migrate to the half-cells to neutralize these charge imbalances. Cations from the salt bridge move toward the cathode where there is an excess of negative charge, while anions migrate toward the anode where there is an excess of positive charge. This movement helps to maintain electrical neutrality in each half-cell, thereby allowing the reaction to continue smoothly and the flow of electrons to persist. By facilitating the balance of charges, the salt bridge plays a crucial role in maintaining the functionality of the electrochemical cell.