Yes, pH and conductivity are related, but not linearly or in an absolute manner. A
pH sensor responds solely to H+ in a solution, whereas in conductivity the
sensors measure the activity of all charged ions (anions and cations) present in a solution. The higher the concentration of ions, the higher the conductivity. Furthermore, the mobility of an ion has an enhancing impact on conductivity. Among the common ions in a solution, the most mobile cation is the Hydrogen ion [H+] with a value of 350 units, and the most mobile anion is the Hydroxyl ion [OH-], 199 units. Other common ions have values ranging between 40 and 80 units. This means strongly acidic (or strongly basic) solutions will have high conductivities. Since pH is a measure of the concentration of Hydrogen ions, the following rules apply: In acidic solutions (< pH 7): the lower the pH (i.e. the higher the H+ concentration) the higher the conductivity. In alkaline solutions (> pH 7): the conductivity increases with increase of the pH (increase of OH- ion). Neutral pH (pH 7) is due to equal concentration of H+ and OH- ions. But it does not mean the solution does not contain any other ions that would contribute to the conductivity of the solution. Let's consider an example: pH of deionized water is theoretically 7.0 and conductivity is 0.055 µS/cm. If you add NaCl salt to it, the resulting NaCl solution will still be of neutral pH, but the conductivity of the solution could greatly increase depending on the amount of NaCl added. In summary: pH and conductivity of a sample must be determined separately for each of the samples and cannot be theoretically correlated.