# Decomposition Potential and Its Significance in Electrolysis Decomposition potential is an important concept in electrochemistry and electroanalytical chemistry. It is particularly relevant to the electrolysis of solutions containing ionic species and helps explain the minimum voltage required to bring about a continuous electrode reaction. In practical electrolysis, simply immersing two electrodes in an electrolyte and applying a small potential difference does not necessarily produce an observable chemical change. A certain minimum applied potential is required before the desired electrode reaction proceeds at an appreciable and continuous rate. This minimum potential is called the decomposition potential. The decomposition potential may be defined as the minimum external applied potential difference required to cause continuous electrolysis of an electrolyte under specified experimental conditions. In other words, it is the minimum voltage at which the current begins to increase significantly and the products of electrolysis are continuously formed at the electrodes. Below this potential, although some current may flow because of capacitive effects, leakage, or other processes, sustained electrolysis does not occur at a significant rate. For example, consider the electrolysis of hydrochloric acid using platinum electrodes. Hydrogen ions are reduced at the cathode to produce hydrogen gas, while chloride ions or water undergo oxidation at the anode depending on the conditions. The applied potential must overcome the thermodynamic electrode potential requirements as well as several practical factors before a continuous current and visible gas evolution are obtained. The potential at which this sustained process begins is associated with the decomposition potential. The decomposition potential is closely related to the electrode potentials of the cathodic and anodic reactions. Thermodynamically, the minimum potential required for an electrochemical reaction can be estimated from the difference between the equilibrium potentials of the two electrodes. However, the experimentally observed decomposition potential is generally higher than the theoretical value. This difference arises mainly because of overvoltage or overpotential, solution resistance, concentration polarization, and other kinetic limitations. The theoretical decomposition voltage can be