I was reading about electrochemical cells and I really don't understand why a salt bridge is needed. Can't you just combine the solutions? I've found a lot of webpages explaining electrochemical cells but strangely enough none of them seem to find this important enough to explain. All thoughts appreciated :)
The use of a salt bridge is to maintain the electrical neutrality throughout the cell.
A salt bridge will allow the movement of ions. Electrons flow from anode to cathode.Due to this a negative charge will be developed in the cathode and a positive charge in the anode.This charge developed will oppose the electron flow (current from anode to cathode) and at one level the electron flow will be ceased.So the cell's action will be stopped. So in order to prevent this, salt bridges are used.
There is a similar question in this site.Please refer that.
There are a lot of cases where you can work without a salt bridge. If the two reactions(reduction and oxidation) don't interfere with each other, you can just let the solution be in a single pot.
It is only there to separate the two solutions and still maintain ionic contact.