glaselektroods

Glass electrodes are a type of ion-selective electrode used to measure the hydrogen ion activity in a solution, effectively determining its pH. The core of a glass electrode is a thin glass bulb made of a special type of glass, typically a silicate glass containing lithium, sodium, and calcium oxides. This glass is permeable to hydrogen ions.

When the glass bulb is immersed in a solution, a hydrated layer forms on its surface. Within this layer, hydrogen ions exchange with alkali metal ions in the glass. This exchange creates a potential difference across the glass membrane, which is dependent on the difference in hydrogen ion concentration between the inner filling solution of the electrode and the outer sample solution. The inner filling solution is usually a buffer solution of known pH.

A reference electrode, such as a calomel electrode or a silver/silver chloride electrode, is also immersed in the sample solution and connected electrically. The potential difference between the glass electrode and the reference electrode is then measured by a pH meter. This measured potential is proportional to the logarithm of the hydrogen ion activity, according to the Nernst equation. Calibration with standard buffer solutions of known pH is essential for accurate measurements. Glass electrodes are widely used in various fields, including chemistry, biology, environmental monitoring, and medicine.