Question

What is the work of salt bridge?

• A. Maintains the electric neutrality in internal circuit.
• B. It transfers the electrons from negative rod to positive rod.
• C. Cools down the cell by injecting ions into electrolytes.
• D. It accelerates the equilibrium.

Answer 1

The correct option is A Maintains the electric neutrality in internal circuit.

The purpose of a salt bridge is not to move electrons from the electrolyte, rather to maintain charge balance because the electrons are moving from one half cell to the other.

The electrons flow from the negative electrode to positive electrode. The oxidation reaction that occurs at the anode generates electrons and positively charged ions. The electrons move through the wire (and your device, which I haven't included in the diagram), leaving unbalanced positive charge in this vessel. In order to maintain neutrality, the negatively charged ions in the salt bridge will migrate into the anodic half cell. A similar (but reversed) situation is found in the other cell, where $C{u}^{2+}$ ions are being consumed, and therefore electroneutrality is maintained by the migration of $K^{+}$ ions from the salt bridge into this half cell.