reduction and oxidation potentials the standard electrode potentials

n an electronic conductor an electric current is the result of an anet movement of electrons in the structure of the conductor when an electrical potential is applied . Electrons have negligible mass compoared with the remainder of the structure and the flow of electricity is not accompanied by a significant movement of matter.Electrolytic coductors contain mobile ions which carry an electrical charge .when an electrical potential is applied these ions will move in the direaction appropriate to their charge.As in electronic conductance the electric current is a movement of electrical charge but this time the charge is carried by ions of significant mass and electrolytic conductance is accompanied by mass transfer conductors may exhibit acombination of electronic and electrolytic conduction but frequently the proportion of one type is so dominating that it is permissible to assume that the conduction is entirly by the dominating mechanism.This property of electrolytic conduction plays amajor role in some of processes and phenomena important to the metallurgist -corrosion and oxidation of metals, electroplating , electropolishing electrolytic extraction and refining of metas for example,

It has been demonstrated that the condition of chemical equilibrium can often be perdicated by thermodynamic considerations and therfore thetendency of areaction to proceed can be measured.The thermodynamic approach dose not however, give any indication of the rate at which a reaction will proceed,and two examples of methallurigically phenomena show the importance of the study of the mechanism and rate of reaction.If aplain carbon steel in the austenitic stracture say at 850c is quenched in watera metastable martensitic structure is produced.this structure will tend to transform to a mixture of ferrite and cementite of lower free energy but the rate of transformation at room tempreature is so slow that the martensite remains apparently unchanged .Tempering at 650 allows the transformation to be completed within an hour.The reaction between carbon and oxygen in liguid steel to form carbon monoxide is accompanid by a substantial negative free energy change but the the carbon and oxygen contents can be raised well above the equilibrium values without any apperciable reaction. If an inrt gas such as argon is bubbled through the liguid steel ,introdusing suitable nuclei for reaction avigorous boil caused by carbon monoxide gas evaluation can be produced ,