Explain voltaic cells and salt bridges?

Question

For voltaic cells, how do salt bridges come into play? If the ions actually move through the salt bridge, why cant the solutions just be mixed?

Answer 1

Good Q!

If you just mixed the solutions, you'd have the solution from the anode compartment in the cathode compartment. For example, if you have the Zn/Zn2+//Cu2+/Cu cell and you mixed the solutions, the Zn would react directly with the Cu2+ solution, rather than sending electrons through the external circuit.

As you say, ions move through the bridge, but these are ions that do not take part in the electrochemical reaction.

Answer 2

You are correct. A salt bridge allows ion flow to maintain a balance of charge between reaction cells