What function does the salt bridge serve in an electrochemical cell?

In an electrochemical cell, the salt bridge plays a crucial role in maintaining electrical neutrality by allowing ionic flow between the two half-cells. As a redox reaction occurs, electrons flow through an external circuit from the anode to the cathode, causing changes in charge. This buildup of positive or negative charge in the respective half-cells can impede the reaction.

The salt bridge contains an electrolyte solution, typically a gel or a liquid that has ions present, which can migrate to balance the charge by compensating for the loss or gain of electrons. For instance, if electrons leave the anode half-cell, positive ions from the salt bridge will move toward the anode, while negative ions will move toward the cathode, thus maintaining the electrical neutrality of the overall system. This function is vital for the continuous operation of the electrochemical cell, enabling a sustained flow of electricity.

This role of the salt bridge distinguishes it from the other options. Connecting the two half-cells electrically focuses on electron flow, while maintaining concentration of reactants refers more to the solution within the half-cells themselves rather than the balance of charges. Allowing the transfer of electrons primarily describes the external circuit rather than the role of the salt bridge. Therefore, the