Question

In an experiment set up for the measurement of EMF of a half cell using a reference electrode and a salt bridge, when the salt bridge is removed, the voltage:

• A. Does not change
• B. Increase to maximum
• C. Decreases to half the value
• D. Drops to zero

Answer 1

Answer: (D)

Drops to zero

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 anode to the cathode. The oxidation reaction that occurs at the anode generates electrons and positively charged ions. The electrons move thrown the wire (and your device, which I haven't included in the diagram), leave 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 and therefore electroneutrality is maintained by the migration of $K^{+}$ ions from the salt bridge into this half cell.