Detailed Explanation of the Conductivity and Electrical Conductivity of Pure Water and Their Relationship with Resistivity

Table of Content [Hide]

Water contains various dissolved salts, existing in ionic form. When a pair of electrodes are inserted into the water and an electric field is applied, the charged ions move in a specific direction. Anions move towards the anode, and cations move towards the cathode, causing the aqueous solution to conduct electricity. The strength of water's conductivity is called conductivity S (or resistivity). Conductivity reflects the amount of salt in the water and is an important indicator of its purity. The purer the water, the lower the salt content, the higher the resistance, and the lower the conductivity. Ultrapure water conducts almost nothing. The magnitude of conductivity is equal to the reciprocal of the resistance. S = 1/R, where R is the resistance. The unit of conductivity (S) was formerly expressed in ohms. Currently, the commonly used international unit for conductivity is the Siemens (S), denoted by S or μS.

Conductivity k = SQ = 1/ρ, where ρ represents resistivity.

Since dissolved salts in aqueous solutions exist in ionic form and are electrically conductive, conductivity can indirectly indicate the content of dissolved salts (salt content).

These concepts are crucial for water quality control, standards, and monitoring in demineralized water treatment.

References

PREV: Microfiltration Technology and Its Characteristics

NEXT: Commonly Used Sample Preservation Techniques for Laboratory Water – Table 2 (Residual Chlorine, Oils, Carbon, etc.)