[One Armed Scissor]

I was just wondering... what exactly is the function of that thing in the middle? I mean... the redox only requires some electrons to go from the anode to the cathode (with the anode donating the electrons and cathode recieving them). Why must we balance the charges on the two sides, and what good does the anion/cation flow through the salt bridge do?

Thanks for clearing this up. It's been bugging me for a while and I'm afraid of sounding stupid to mention it to my teacher :p

[Mitch]

The first thing to know about any circuit is that their needs to be a flow of charge. If the electrons go to the cathode how does this completer the circuit alone? You need negative charge carriers to take the charge back to the anode and repeat the process. The salt bridge ions facillitate this role.

[Donaldson Tan]

in cases whereby the salt bridge is absent, u would notice that both the cathode and anode are immersed in the same solution, thus there wouldn't be a need for the salt bridge to complete the circuit as the solution itself closes the circuit.

[chemicalLindsay]

this has sort of been bugging me to as there was no matter where I looked no explanation to this.So are you saying or this is what im saying if I had a beaker filled with sodium chloride solution (concentrated) and I had an iron electrode and a zinc electrode connected together by an external circuit than  the concentrated sodium chloride solution would ( contanianing both anions and cations) act as both the electrolyte and salt bridge in a way of the cell.

[Donaldson Tan]

the salt bridge closes the electrochemical cell circuit. it's the equivalent of a wire for aq. electrolytes.