The reference electrode, the reference electrode, is used as a reference and comparison electrode when measuring various electrode potentials. The electrode to be measured and the reference electrode of which the potential value of the electrode is accurately known are formed into a battery, and the value of the electromotive force of the battery is measured to calculate the electrode potential of the electrode to be measured. The electrode reaction performed on the reference electrode must be a single reversible reaction with stable and reproducible electrode potential. Usually a slightly soluble salt electrode is used as the reference electrode, and the hydrogen electrode is only an ideal but not easy to realize reference electrode. A list of commonly used reference electrodes is given below.
The electrode used for reference comparison when measuring electrode potential. Strictly speaking, the standard hydrogen electrode is only an ideal electrode, and it is not practical. Therefore, in the actual measurement of the electrode potential, an electrode whose electrode potential is precisely known and which is very stable is always used as a comparison electrode. By measuring the electromotive force of the battery composed of such electrodes and the electrode under test, the electrode potential of the electrode under test can be calculated.
The electrode reaction carried out on the reference electrode must be a single reversible reaction, the exchange current density is large, the fabrication is convenient, the reproducibility is good, and the electrode potential is stable. Generally, a refractory salt electrode is used as a reference electrode. The reference electrode should not be easily polarized; if polarization occurs once the current is too large, the electrode potential should be able to quickly recover to its original value after power failure; when the temperature changes, the hysteresis change of the electrode potential should be small.
When the pipe metal is in some kind of electrolyte, then the potential of the pipe is not stable. A reference electrode is a half-cell with a stable, reversible electrochemical potential determined by the property of a single, reversible reaction. The stability of the reference electrode makes it very useful as an electrical reference point or for measuring the potential of other metals located in soil or water. When the reference electrode is connected through a voltmeter to other metals in soil or water, the reference electrode becomes a semi-corrosion cell. Reference electrodes used to measure the potential of buried or submerged pipelines usually have potential values that are more positive than those of steel.
