Innovative school-level quantitative chemistry experimental technique (i): pH measurement by antimony electrode

Abstract

This paper introduces the principles of pH measurement by antimony/copper(II) combination electrodes, use of an innovative mini “salt-plug” and details for the construction of the electrodes and an electronic sensor. Raw e.m.f. signals generated by the combination electrode are amplified by the sensor which is pre-set to give an analogue output voltage of 10 mV per pH. The voltage displayed by a commercial low-cost digital multimeter (DMM) can be treated as the pH value. The “DMM display” technique works for measurements of conductance and colour intensity as well as pH, provided that suitable sensors are used.