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Potentiometry passively measures the potential of a solution between two electrodes, affecting the solution very little in the process. One electrode is called the reference electrode and has a constant potential, while the other one is an indicator electrode whose potential changes with the sample's composition. Therefore, the difference in ...
The indicator electrode forms an electrochemical half-cell with the interested ions in the test solution. The reference electrode forms the other half-cell. The overall electric potential is calculated as = +. E sol is the potential drop over the test solution between the two electrodes. E cell is recorded at intervals as the titrant is added ...
An ion-selective electrode (ISE), also known as a specific ion electrode (SIE), is a simple membrane-based potentiometric device which measures the activity of ions in solution. [1] It is a transducer (or sensor ) that converts the change in the concentration of a specific ion dissolved in a solution into an electrical potential .
The Gran plot is based on the Nernst equation which can be written as = + {+} where E is a measured electrode potential, E 0 is a standard electrode potential, s is the slope, ideally equal to RT/nF, and {H +} is the activity of the hydrogen ion.
A potentiometer being calibrated and then measuring an unknown voltage. R 1 is the resistance of the entire resistance wire. The arrow head represents the moving wiper.. In this circuit, the ends of a uniform resistance wire R 1 are connected to a regulated DC supply V S for use as a voltage divider.
Electrochemical stripping analysis is a set of analytical chemistry methods based on voltammetry [1] or potentiometry [2] that are used for quantitative determination of ions in solution. [3] Stripping voltammetry (anodic, cathodic and adsorptive) have been employed for analysis of organic molecules as well as metal ions.
A platinum wire electrode is immersed in a saturated aqueous solution of quinhydrone, in which there is the following equilibrium C 6 H 6 O 2 ⇌ C 6 H 4 O 2 + 2H + +2e −. The potential difference between the platinum electrode and a reference electrode is dependent on the activity, +, of hydrogen ions in the solution.
Some commercially available reference electrodes have an internal junction which minimizes the liquid junction potential between the sample solution and the electrolyte in the reference electrode (KCl). The internal electrolyte is at fixed composition and the electrode response is given by the Nernst equation: E = E 0 − RT/F ln a F −, where: