Temperature affects the pH measurement in two ways. The first is a change in pH due to changes in dissociation
constants of the ions in the solution being measured. This implies that as solution’s temperature changes, the pH
value also changes. Presently available instrumentation cannot account for this change because the dissociation
constants vary from solution to solution.
The second reason temperature affects the pH measurement, is glass electrode resistance. Since the glass
measuring electrode is an ionic conductor, it stands to reason that the resistance of the glass will change as the
solution temperature changes. As temperature rises, resistance across the glass bulb decreases. This change in
resistance versus temperature is constant and can be calculated depending on the specific type of glass
formulation of the electrode.