Define Principle behind the functioning of a pH meter?

Principle Hydrogen ions in solution, like other ionic species, conduct an electric current. When a glass electrode is dipped in a solution containing hydrogen ions, a potential difference develops across a very thin glass membrane separating two solutions of different hydrogen ion concentrations - one within and the other outside the glass electrode. A pH meter is an electronic voltmeter that measures this difference of potential and through its internal calibration, converts it to a pH reading which is displayed on a scale.

The scale is normally taken extending from 0 to 14 pH units with a least count of 0.05 pH units or better. A pointing needle moves across the graduated scale and the pH of the solution can be read directly on the scale. These days digital pH meters are becoming more popular as compared to scale - needle instruments. With a review of the principle and functions of the pH meter, we are now ready to get started with the experiments related to pH and buffer solutions.