In a galvanic cell, the salt bridge is a crucial component that connects the two half-cells. Let's understand its functions and properties step by step.

Step 1: Purpose of Salt Bridge
A galvanic cell consists of two half-cells, each containing an electrode immersed in an electrolyte. The salt bridge completes the electrical circuit by allowing the flow of ions between the half-cells, maintaining electrical neutrality.

Step 2: Composition and Function
The salt bridge is typically a U-shaped tube filled with an inert electrolyte (e.g., KCl or KNO₃ in agar gel). Its key functions are:

• Prevents the accumulation of charge in the half-cells by allowing ions to migrate.
• Maintains the continuity of the current by completing the circuit.

Step 3: Chemical Participation
The salt bridge does not participate chemically in the cell reaction. The ions in the salt bridge (e.g., K⁺ and Cl⁻) are inert and do not react with the electrolytes or electrodes.

Step 4: Diffusion Control
The salt bridge actually facilitates the controlled diffusion of ions from one half-cell to the other to balance charge, rather than stopping it. It prevents direct mixing of the two electrolytic solutions, which could cause side reactions or precipitate formation.

Step 5: Ensuring No Mixing
The salt bridge ensures that the two electrolytic solutions do not mix, thereby avoiding any unintended chemical reactions between them.

Final Answer: Based on the above, the correct statement is: "does not participate chemically in the cell reaction."

Related Topics

Galvanic Cell Operation: A galvanic cell converts chemical energy into electrical energy through spontaneous redox reactions. Oxidation occurs at the anode, and reduction occurs at the cathode. The salt bridge is essential for maintaining charge balance and allowing the cell to function continuously.

Electrochemical Series: The tendency of an electrode to lose or gain electrons is determined by its standard electrode potential, which influences the cell potential. The salt bridge helps in achieving the theoretical cell potential by minimizing junction potential.

Formulae

The cell potential (EMF) is given by the Nernst equation: $E=E_0-\frac{0.059}{n}\log Q$ where $E$ is the cell potential, $E_0$ is the standard cell potential, $n$ is the number of electrons transferred, and $Q$ is the reaction quotient. The salt bridge helps maintain the proper ion concentrations for accurate EMF measurement.