Potentiometrisissa

Potentiometrisissa refers to potentiometric measurement techniques. A potentiometer is an instrument that measures an unknown voltage by balancing it against a known variable voltage. This balance is typically achieved by adjusting a slider on a resistive wire, effectively changing the resistance and thus the voltage drop. When the unknown voltage is precisely balanced by the known voltage, no current flows between the two, and the unknown voltage can be determined from the position of the slider and the known voltage.

Potentiometric methods are widely used in analytical chemistry and electrochemistry for determining the concentration of ions in a solution, measuring electrode potentials, and controlling electrochemical reactions. In these applications, a potentiometric sensor, such as an ion-selective electrode or a pH electrode, generates a voltage proportional to the concentration of a specific analyte. This voltage is then measured using a high-impedance voltmeter, which acts as a potentiometer. The high impedance ensures that negligible current is drawn from the sensor, thereby minimizing polarization effects and ensuring an accurate voltage reading.

The principle of potentiometry relies on the Nernst equation, which relates the electrode potential to the concentration of the ion being measured. By calibrating the system with solutions of known concentrations, a calibration curve can be established, allowing for the determination of unknown concentrations. Potentiometric titrations are another important application, where the voltage change is monitored as a titrant is added to a sample. The equivalence point of the titration is identified by a significant change in potential.