Areal capacitance deserves its own name and symbol, also in colloid chemistry

Areal capacitance, that is, electric capacitance per unit of surface area, is an important physical quantity, especially in electrochemistry and in colloid chemistry. In handbooks and in scientific papers, the symbol C which normally denotes capacitance is also used for areal capacitance, although capacitance and areal capacitance are two different physical quantities, which have different units (F, and F/m2, respectively), and different numerical values. Using the same name and symbol for two different physical quantities is misleading, especially when the both quantities appear in the same text. The present author postulates that the term “areal capacitance” and the symbol Ξ (with corresponding subscript when applicable) are always used when areal capacitance is meant, to clearly distinguish it from capacitance. The rationale for such a name and symbol is discussed.