A conductivity cell, also known as a conductance cell, is the fundamental component of a conductometric measuring system.
It consists of two electrodes immersed in the solution to be analyzed, and these electrodes are typically made of inert, conductive materials such as platinum, gold, or graphite.
Key aspects of the conductivity cell include:
1. Electrodes of Conductivity Cell
The electrodes are often coated with a thin layer of platinum black to increase their effective surface area and minimize polarization effects, which could interfere with the accuracy of measurements.
2. Electrical Circuit
The electrodes are connected to an external circuit that applies an alternating voltage, generating an electric field in the solution.
The current flowing between the electrodes is proportional to the solution’s conductivity.
3. Cell Constant (K)
The cell constant (K) is a critical parameter, defined as the ratio of the distance between the electrodes (d) to their effective surface area (A):
The cell constant depends on the geometry and dimensions of the electrodes and must be determined through calibration using standard solutions with known conductivity.