What purpose does the salt bridge serve in a galvanic cell?

In a galvanic cell, the salt bridge plays a crucial role in maintaining electrical neutrality within the cell as chemical reactions occur. When the oxidation and reduction reactions transpire at the electrodes, electrons are transferred, leading to a separation of charge. This separation can create an imbalance that would eventually halt the cell's operation if not corrected.

The salt bridge, typically filled with an electrolyte solution, allows ions to flow between the two half-cells. This movement of ions counteracts the buildup of positive charge in the oxidation half-cell and negative charge in the reduction half-cell, thereby maintaining electrical neutrality. By allowing ions to migrate, the salt bridge helps keep the circuit closed, allowing the cell to continue functioning efficiently.

The other options do not accurately reflect the primary function of the salt bridge. While connecting the electrodes directly may be required in certain setups, that is not the specific role of the salt bridge. Preventing reactions between electrodes does not capture its function accurately, as reactions are essential to the cell's operation. Generating hydrogen gas is unrelated to the salt bridge’s purpose, as hydrogen production would depend on the specific reactions taking place at the electrodes themselves rather than the salt bridge function.