I don't understand how a salt bridge work exactly: what happens inside it and how it affect the cell's lifetime.
I have already read:
What I understand:
The salt bridge's goal is to maintain electro-neutrality in each of the half-cells so that the voltaic cell keeps working and it helps avoiding the mixing of the half-cells' ions in solutions. When the salt bridge is being used in the cell, its ions (anions and cations which constitute the salt bridge's electrolyte) are moving towards the half-cell that attracts them.
What I don't understand:
- Do the salt bridge's ions leave the salt bridge to go all the way within the hall-cells' solutions or do they stay at the border ? Is it the case in all bridges ?
- Do the half-cells' ions move inside the salt bridge or do they stay in the salt bridge at the border solution/salt-bridge ? Is it the case in all bridges ? And is it in the same proportions as the salt bridge's ions ?
- How do the ions move exactly in the salt-bridge ? It seems like the propagation in, let's say agar-agar, is much slower than the displacement of ions in the liquid solutions in the half-cells, is it not a problem for the whole cell ? Is it like a longitudinal wave, ions pushing others ? If so, are they two speeds of propagation (the wave speed and the ions speed) ?
- If ions are moving inside it, we can consider that there is a current in the salt bridge, correct ?
- Are they families of salt bridges depending on how they work ?
- Finally, can the salt bridge be exhausted before the half-cells (whether the solutions or the electrodes) ? It seems the salt bridge is quite small in basic cells examples compared to the sheer volumes of the solutions and sizes of the electrode, thus containing much fewer ions.