Qiwei PHS-3E PH meter (desktop microcomputer) is a PH meter with a relatively large measuring range, the measuring range is -2 ~ 18pH . Data storage and extraction, automatic temperature compensation, convenient and simple operation, stable measurement data.
Glass electrodes are often used to measure the pH value of aqueous solutions. The head of the pH glass electrode is made of a special sensitive film, which is sensitive to hydrogen ions. Concentration and temperature vary. When the solution temperature is 25°C, the electrode potential changes by 59.16mV for every pH change. That is, the theoretical slope coefficient of the electrode.
The glass electrode is used as the indicating electrode, and since its potential does not change with the concentration of hydrogen ions in the measured solution, the reference electrode is generally a calomel electrode. When the hydrogen ion concentration (strictly speaking, the activity) in the solution, that is, the pH value of the solution changes, the potential generated between the glass electrode and the calomel electrode also changes, and the potential change relationship conforms to the following formula:
△E=-58.16×△pH×(273+t℃)/293(mV)
△E: Indicates the change in potential in millivolts. (mV)
△pH: Indicates the change of the pH value of the solution.
t: Indicates the temperature of the solution to be measured (°C).
The measurement of pH value measures the potential difference between two electrodes. When the potential difference generated by a pair of electrodes in the solution is equal to zero, the pH value of the measured solution is the zero potential pH value, which is related to the solution in the glass electrode. The PHS-3E pH meter is equipped with a composite electrode composed of a glass electrode and an Ag-Agcl electrode, and its zero point pH value is 7±0.25pH.


