Final answer:
A glass membrane electrode is primarily used to measure the pH level of a solution by monitoring the concentration of H+ ions.
Step-by-step explanation:
The glass membrane electrode is used to measure the pH of a solution. This type of electrode typically consists of a thin glass membrane that absorbs protons, with an internal Ag/AgCl electrode surrounded by 1 M HCl solution. The voltage output of the glass electrode varies depending on the concentration of H+ ions (protons) in the solution, according to the equation Eglass = E' - (0.0591 V × pH), where E' is a constant characteristic of the electrode. The potential is therefore directly related to the pH level of the solution, which is the negative logarithm of the hydrogen ion concentration. To measure pH, the glass electrode is first calibrated with a known pH solution, and then it is inserted into an unknown solution to determine its pH.