What Is Electrical Conductivity?

Electrical conductivity, a physical concept, can also be called electrical conductivity. The product of this quantity and the electric field strength E in the medium is equal to the conduction current density J. For isotropic media, conductivity is a scalar; for anisotropic media, conductivity is a tensor. In ecology, conductivity is the ability of a solution to conduct current in a number. The unit is expressed in Siemens per meter (S / m). ^[1]

Conductivity is used to describe a substance

The conductivity measurement is usually the conductivity measurement of the solution. The resistivity of a solid conductor can be determined by

The conductivity benchmark in China and many countries is established by relative measurement method, which is a kind of national secondary benchmark.

A high-purity potassium chloride having a purity of better than 99.99% is used as a conductivity reference material in accordance with international recommendations, and the reference solution prepared by it should have an internationally recommended conductivity value. Taking the conductivity of the solution at 25 ° C as the starting point, measure each conductivity constant accordingly, and then calculate the conductivity constant K at other temperatures according to the following formula

K = K ₀ (1-at)

In the formula, K ₀ is the conductivity cell constant at 0 ° C; a is the coefficient of linear expansion of the glass used to make the conductivity cell; t is the temperature of the solution, in ° C.

The above formula is the approximate derivation result, and the difference between the maximum and plus or minus 1xl0 ^-5 will not be exceeded when considering complex situations. Then according to the measured resistance value of each solution on the corresponding conductivity cell at different temperatures, the conductivity of each solution at different temperatures is calculated accordingly. Because the temperature coefficient of the relative change of the conductivity of the conductivity cell is -8.49x10 ^{-6 -1} , and the temperature coefficient of the conductivity of the KCl solution is about + 2x10 ^{-2 -1} . Therefore, if the measured conductivity of 1D, 0.1D and 0.01D solutions at 18 ° C and 20 ° C is consistent with the international recommended values, then this relative measurement method can be considered reliable, which will be compared in future international samples. Was verified. The international recommended value of 20 is the recommended value of IUPAC in 1972 and 1976.