Electrolytic cell reaction which would not occur spontaneously otherwise. A galvanic cell can be considered an electrolytic cell acting in reverse. While electrolytic cells convert electrical energy into chemical energy, galvanic cells convert chemical energy into electrical energy. Galvanic cells are often used in batteries. Michael Faraday defined the cathode of a cell as the electrode to which cations (positively charged ions, like silver ions Ag) flow within the cell, to be reduced by reacting with electrons (negatively charged) from that electrode. Likewise he defined the anode as the electrode to which anions (negatively charged ions, like chloride ions Cl) flow within
Fluoride selective electrode where the fluoride transport number is 1. As transference of charge through the crystal is almost exclusively due to fluoride, the electrode is highly specific to fluoride. The only ion which significantly interferes is hydroxide (OH). Generally such "alkaline error" can be avoided by buffering the sample to a pH below 7. The cell diagram of a typical experimental arrangement is: where: Some commercially available reference electrodes have an internal junction which minimizes the liquid junction potential between the sample solution and the electrolyte in the reference electrode (KCl). The internal electrolyte is at fixed composition and the electrode response