pH temperature compensation

by Vera

The response of an ideal pH electrode is defined by the Nernst Equation: E = Eo - kT·pH

However, the slope or Nernst factor (kT) will change when temperature changes (T is not constant). This change in slope with temperature will be compensated for by a pH meter using Automatic Temperature Compensation (ATC).

This table shows the changes in the Nernst factor at increasing temperatures for the ideal electrode:

Temperature °C      Nernst slope (mV/pH)

            0                    54.20
          10                    56.18
          20                    58.17
          25                    59.16
          30                    60.15
          40                    62.14
          50                    64.12
          60                    66.10
          70                    68.09
          80                    70.07
          90                    72.06

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May 27, 2010
Temperature sensor
by: Will

Automatic temperature compensation requires input from a temperature sensor. In most cases the temperature sensor is integrated in the pH electrode.

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