How the pH/Ion Meter works
pH/Ion Meter is an instrument used to measure the pH value of a solution. The pH meter works on the principle of a primary battery. The electromotive force between the two electrodes of the primary battery is based on Nernst's law, which is related to the properties of the electrode itself and the concentration of hydrogen ions in the solution. There is a corresponding relationship between the electromotive force of the primary battery and the concentration of hydrogen ions, and the negative logarithm of the concentration of hydrogen ions is the pH value. pH/Ion Meter is a common analytical instrument widely used in fields such as agriculture, environmental protection and industry. Soil pH is one of the important basic properties of soil. Factors such as the temperature and ionic strength of the solution to be tested should be considered in the pH determination process.
The structure of the pH/Ion Meter includes a composite electrode and an ammeter. The composite electrode is what we call the indicator electrode and the reference electrode. Generally, the indicator electrodes of the pH meter are glass electrodes. The function of the glass electrode is to be sensitive to the hydrogen ions in the solution, and the potential difference is reflected by the change of the hydrogen ions. The role of the reference electrode is to provide a constant potential as a reference for deviations from the potential. Among the components of the pH meter, the ammeter is used to measure the overall potential. It can capture small potential changes in a circuit with a large resistance and display this change through the ammeter. In order to facilitate the reading, the pH meter has a display function, which is to convert the output signal of the ammeter into a pH reading.
The pH/Ion Meter measures the pH of a solution by potentiometric method. The main parts involved in the measurement of the pH meter are the glass electrode and the reference electrode. The glass electrode is sensitive to pH, and the potential of the reference electrode is stable. Put the two electrodes of the pH meter into the same solution together to form a primary battery, and the potential of the primary battery is the algebraic sum of the potentials of the glass electrode and the reference electrode.
The potential of the reference electrode of the pH/Ion Meter is stable, so when the temperature remains stable, the potential change of the primary battery composed of the solution and the electrode is only related to the potential of the glass electrode, and the potential of the glass electrode depends on the solution to be measured Therefore, by measuring the change of the potential, the pH value of the pH solution can be obtained.