Final answer:
Glass electrodes are limited in measuring pH below 2 and above 10 due to diminished ion exchange efficiency at these extremes and potential damage to the glass membrane, leading to inaccurate pH readings.
Step-by-step explanation:
A glass electrode cannot be used to measure pH below 2 and above 10 due to limitations in the electrode's construction and the chemistry involved. At extreme pH levels, the ion exchange between the solution and the thin glass membrane of the electrode becomes less efficient.
Specifically, at very high pH levels, the glass surface can become deprotonated to a point where it can no longer respond accurately to changes in hydrogen ion concentration. And at very low pH levels, high acidity can lead to the saturation of the glass surface with protons, again diminishing the electrode's responsiveness. Additionally, at these extremes, the glass can be attacked by the solution, affecting its structural integrity and function.
The potential E₀ is constant for a specific glass electrode and is determined during calibration, which sets the baseline for accurate pH measurements. In the pH range of 2 to 10, the potential across the electrode can vary linearly with pH alterations allowing for accurate readings. However, outside this range, the correlation breaks down due to the factors mentioned, and a glass electrode becomes unreliable for pH measurement.