Electrolytic cell electrons from the cathode and deposits on the cathode as sodium metal. NaCl dissolved in water can also be electrolyzed. The anode oxidizes chloride ions (Cl), and Cl gas is produced. However, at the cathode, instead of sodium ions being reduced to sodium metal, water molecules are reduced to hydroxide ions (OH) and hydrogen gas (H). The overall result of the electrolysis is the production of chlorine gas and aqueous sodium hydroxide (NaOH) solution. Commercially, electrolytic cells are used in electrorefining and electrowinning of several non-ferrous metals. Almost all high-purity aluminium, copper, zinc and lead is produced industrially in electrolytic
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