Potential Response of Solid State Potentiometric Chemical Sensors, Theoretical Approach and Teaching Experiment

Njegomir Radić* and Josipa Komljenović
Faculty of Chemical Technology, University of Split, Teslina 10/V, 21000 Split, Croatia. E-mail: njradic@ktf-split.hr

Abstract
Analytical procedures used for qualitative identification or/and quantitative determination of chemical species are based on reaction that takes place in homogeneous or heterogeneous systems. When a solid state potentiometric chemical sensor (PCS) is placed in a solution containing species which can exchange (or reversibly react) with the sensing surface an electrical potential at the surface of a solid material is formed. The species recognition process is achieved with PCS through a heterogeneous chemical reaction at the sensor surface. Reactions that take place in homogeneous solution are also important for the response of a solid state PCS to sensed species in solution. Potentiometric measurements with PCS containing membrane prepared by pressing sparingly soluble inorganic salts can be used for teaching homogeneous and heterogeneous equilibrium. Learning objective is to distinguish between homogeneous and heterogeneous equilibrium, and between single-component and multi-component systems. Homogeneous and heterogeneous systems may be a single chemical or may consist of several components.

Key words: analytical chemistry, potentiometrc sensors, teaching learning theory