Final answer:
In an electrochemical cell, negatively charged ions migrate towards the anode, and positively charged ions migrate towards the cathode through the salt bridge to maintain electrical neutrality and complete the electrical circuit.
Step-by-step explanation:
In the salt bridge of an electrochemical cell, negatively charged ions (anions) migrate towards the anode while positively charged ions (cations) migrate towards the cathode.
This migration facilitates the completion of the electrical circuit and aids in maintaining electrical neutrality by compensating for the charges in each half cell. For example, as copper metal is oxidized in one half cell, Cu2+ ions are produced, and positively charged sodium ions from the salt bridge move into this solution to maintain electrical neutrality. Conversely, nitrate ions, which are negatively charged, move from the salt bridge into the solution where zinc metal is dissolving to neutralize the increasing positive charge from Zn2+ ions. The salt bridge ensures continuity of the electrical circuit and prevents the build-up of charge that would otherwise halt the reaction.