Section 23.

Part 23 Potentiometry

Reference Electrodes A reference is a cathode that has the half-cell potential known, steady, and totally heartless to the sythesis of the arrangement under study. In conjunction with this reference is the pointer or working terminal , whose reaction relies on the analyte fixation.

Reference Electrodes Ideal Reference Electrode: Is reversible and complies with the Nernst condition Exhibits a potential that is steady with time Returns to its unique potential in the wake of being subjected to little streams Exhibits little hysteresis with temperature cycling

Reference Electrodes

Reference Electrodes Calomel Electrodes:

Reference Electrodes Silver/Silver Chloride Electrodes :

Metallic Indicator Electrodes There are four sorts of metallic pointer terminals: Electrodes of the main kind. Anodes of the second kind. Anodes of the third kind. Redox cathodes.

Metallic Indicator Electrodes

Membrane Indicator Electrodes Properties: Minimal solvency. An essential property of a particle particular medium is that its solvency in analyte arrangements approaches zero. Electrical conductivity. A film must show some electrical conductivity, but little. By and large, this conduction appears as relocation of separately charged particles inside the layer. Particular reactivity with the analyte. A film or a few animal categories contained inside the layer grid must be prepared to do specifically restricting the analyte particle. Three sorts of official: Ion-trade Crystallization Complexation

Membrane Indicator Electrodes Glass Electrodes:

Membrane Indicator Electrodes Glass Electrodes: Potential The limit potential. The capability of the inward Ag/AgCl reference anode. A little asymmetry potential.

Membrane Indicator Electrodes Alkaline Error Selectivity Coefficients Acid Error

Membrane Indicator Electrodes Crystalline Membrane Electrodes:

Membrane Indicator Electrodes Fluoride Electrode:

Membrane Indicator Electrodes Liquid Membrane Electrodes: Cation exchangers Anion exchangers Neutral macrocyclic mixes, which specifically complex certain cations

Membrane Indicator Electrodes

Ion-Selective Field-Effect Transistors (ISFETs)

Molecular-Selective Electrode Systems Gas-Sensing Probes: Microporous materials-made from hydrophobic polymers that have a porosity of around 70% and a pore size of under 1  m, and are around 0.1mm thick. Homogeneous movies strong polymeric substances through which the analyte gas goes by dissolving in the layer, diffusing, and after that desolvating into the interior arrangement. They are generally more slender than microporous keeping in mind the end goal to rush the exchange of gas and in this way the rate of reaction of the framework.

Molecular-Selective Electrode Systems Gas-Sensing Probes:

Instruments for Measuring Cell Potentials Direct-Reading Instruments Commercial Instruments Utility General-reason Expanded-scale Research

Direct Potentiometric Measurements The Sign Convention and Equations for Direct Potentiometry The Electrode Calibration Method Inherent Error in the Electrode Activity Versus Concentration Calibration Curves for Concentration Measurement Standard Addition Method Potentiometric pH Measurements with a Glass Electrodes Summary of Errors Affecting pH Measurements with the Glass Electrode The Operational Definition of pH

Potentiometric Titrations Schematic representation of a programmed potentiometric titrator formulated by Lingane in 1948.

References http://ull.chemistry.uakron.edu/systematic/Potentiometry/http://chem.ch.huji.ac.il/~eugeniik/instruments/electrochemical/potentiometric_titrators.htm http://www.fz-juelich.de/isg/sensorik/bcs-isfet-e.html http://www.chemistry.msu.edu/courses/cem333/Chapter23,potentiometry.PDF