Fuel Cells

[yusufhamood]

Why does the pH of the electrolyte near the cathode increase and reach a constant value when the cell begins to produce energy?
 
Thanks in advance

[ahnafamer]

Oxygen is reduced, forming OH– ions (remember OIL RIG!!) at the cathode of the fuel cell, so an increase in pH occurs at this electrode initially (due to OH- ions being basic). The OH– ions migrate to the anode, through the porous electrode where they are consumed. Once the rate of production of OH– ions at the cathode becomes equal to the rate at which they depart, the pH near the electrode will be constant.