I am reviewing the basics of high school chemistry, using "Chemistry for Dummies".
The book contains a description of the workings of a Daniel Cell, composed of the following:
-A piece of zinc metal in a solution of zinc sulfate (anode)
-A piece of copper metal in a solution of copper (II) sulfate (cathode)
-A wire between the anode and the cathode
-A salt bridge, filled with a concentrated salt solution, between the two solutions
I do not understand why a salt bridge is necessary, in addition to the wire between the two electrodes, for electrons to flow.
More specifically, since copper ions accept electrons from zinc metal, and copper and zinc are conductors, why can't electrons just move from the anode to the cathode, through the wire, as if "pulled" by copper ions in the copper (II) sulfate ? Why do we need the circuit to be closed by a bridge?
Could somebody explain what's missing in my "reasoning"?
Thank you very much for your help.