referenssielektrodiin

Referenssielektrodi (reference electrode) is a half-cell in electrochemistry that provides a stable, well-defined potential against which the potential of a working electrode can be measured. In potentiometric and voltammetric measurements, the reference electrode should carry little to no net current and maintain a constant potential despite changes in the test solution, making it a reference point for accurate potential readings.

Common aqueous reference electrodes include the silver/silver chloride electrode (Ag/AgCl) in saturated potassium chloride (KCl) and the calomel electrode (Hg2Cl2, often in saturated KCl). These electrodes rely on stable redox couples and well-controlled electrolyte compositions. The standard hydrogen electrode (SHE) defines the conventional zero of the electrochemical scale, but it is mainly of theoretical importance and is impractical for routine use. Non-aqueous and specialized references exist for non-aqueous solvents or extreme conditions, such as Ag+/Ag in organic media.

Construction typically involves a metal or redox-active element in contact with an electrolyte, housed in a reference body with a salt bridge or porous junction to minimize contamination of the test solution while allowing ionic contact. The choice of reference depends on the required stability, compatibility with the solvent, and the possibility of junction potential drift.

Applications span potentiometry, pH measurements, and various electroanalytical techniques, including corrosion studies and battery research. Maintenance focuses on keeping the reference filled with the correct electrolyte, preventing drying or contamination, and periodic calibration against standards. Safety considerations include handling mercury-containing references and proper disposal where applicable.