[Darren]

What will be evolved at the anode? Using electrode potentials, bromine will be evolded. But doing the actual experiment, do you actually observe bromine discharging at the anode? It seems more like oxygen gas being discharged instead. Why doesnt the observation follow the prediction using electrode potentials?

[UG]

Why doesnt the observation follow the prediction using electrode potentials?

Could be non-standard conditions, or overpotential

[Darren]

Why doesnt the observation follow the prediction using electrode potentials?

Could be non-standard conditions, or overpotential

What do you mean by overpotential? The potential of the batteries applied to it?

[Borek]

http://en.wikipedia.org/wiki/Overpotential

Overpotential is an electrochemical term which refers to the potential difference (voltage) between a half-reaction's thermodynamically determined reduction potential and the potential at which the redox event is experimentally observed.