Electrochemical Definitions and Terminology

As in all other disciplines, electrochemistry has its own terminology with which one deeds to be familiar before studying specific electrochemical methods. 

Two types of processes Occur at electrodes. Ohe kind includes those in which charge (e.g., electrons) is transferred across the electrode-solution interface. In these processes, actual oxidation or reduction occurs they are governed by Faraday s laws, and are called faradaic processes. 

Under some conditions an electrode may be in a potential region where charge-transfer reactions do not occur because they are either thermodynamically or kinet-ically unfavorable. However, such processes as adsorption can occur, and the structure of the electrode-solution interface can change, causing transitory changes in current and/or potential. These processes are called nonfaradaic processes. 

Charging Current. An important example of a nonfaradaic process is that of the charging of an electrode (see Fig. 1.1). At some potential a (Fig. 1.1 A) there is a 

Figifre 1.1. Arrangement of charge at the electrode-solution interface. In case B, the electrode is at a more negative potential than in A hence the greater amount of negative charge at the electrode surface in B. 

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