The measuring electrode tip for a pH electrode is commonly made of which material?

The measuring electrode tip for a pH electrode is commonly made of which material?

• A. AgCl
• B. Pt
• C. Au
• D. Cu

Answer: (A)

The main idea is that pH measurement relies on a glass sensing electrode whose tip is made of special glass that responds to hydrogen ion activity. The glass surface develops a potential that changes with pH because of ion exchange at the glass–solution interface. In contrast, the reference electrode provides a stable baseline potential, and that part of the probe is typically a silver/silver chloride (AgCl) system. So AgCl is associated with the reference half-cell, not the sensing tip. The metals listed (Pt, Au, Cu) aren’t used as the pH-sensing tip. This distinction helps you see why the measuring tip material is glass, while AgCl serves in the reference electrode to stabilize the measurement.

The main idea is that pH measurement relies on a glass sensing electrode whose tip is made of special glass that responds to hydrogen ion activity. The glass surface develops a potential that changes with pH because of ion exchange at the glass–solution interface. In contrast, the reference electrode provides a stable baseline potential, and that part of the probe is typically a silver/silver chloride (AgCl) system. So AgCl is associated with the reference half-cell, not the sensing tip. The metals listed (Pt, Au, Cu) aren’t used as the pH-sensing tip. This distinction helps you see why the measuring tip material is glass, while AgCl serves in the reference electrode to stabilize the measurement.