Components of a pH meter (acidity meter)

　　PH meter is a commonly used teaching instrument . PH acidity meter products are used to accurately measure the pH value of liquid media and are widely used in industries such as industry, scientific research, food, and environmental protection. When using a PH meter, users need to have a certain understanding of its components, so that it will be more convenient to use. Today, the editor will introduce the components of the PH meter in detail, hoping to help everyone.

　　The pH meter consists of three parts:

　　1. A reference electrode;

　　2. A glass electrode, whose potential depends on the pH of the surrounding solution;

　　3. An ammeter that can measure a small potential difference in a circuit with extremely high resistance.

　　The following is a description of the main functions of each component:

　　1. The basic function of the reference electrode is to maintain a constant potential as a reference for measuring various deviations from the potential. Silver-silver oxide electrode is currently the most commonly used reference electrode in pH.

　　2. The function of the glass electrode is to establish a potential difference that responds to changes in the activity of hydrogen ions in the measured solution. Placing a pH-sensitive electrode and a reference electrode in the same solution forms a primary cell, the potential of which is the algebraic sum of the potentials of the glass electrode and the reference electrode. E cell = E reference + E glass. If the temperature is constant, the potential of this cell changes with the pH of the solution to be measured. It is difficult to measure the potential generated by the cell in the pH meter because its electromotive force is very small and the impedance of the circuit is very large (1-100MΩ); therefore, the signal must be amplified to be sufficient to drive a standard millivoltmeter or milliammeter.

　　3. The function of the ammeter is to amplify the potential of the primary battery several times. The amplified signal is displayed through the meter. The degree of deflection of the meter pointer indicates the strength of the signal it drives. For the needs of use, the dial of the pH ammeter is engraved with the corresponding pH value; while the digital pH meter directly displays the pH value in numbers.