Innovative school-level quantitative chemistry experimental technique (III): A conductivity meter designed for micro-scale use in schools

Abstract

The paper is a continuation of Part (II) of the article [1] published in AJCE Vol 10 No.2, July, 2020. It also advocates the use of “DMM display” technique in which a single piece of instrument, a digital multi-meter (DMM), is used as a terminal display for more than one type of experiment. Sensor circuit design aims at providing a “unit-free” display situation in which students feel less threatening, i.e. a “user-friendly” situation for school-level experimentation. The designed electronic sensor, coupled with an innovative miniature conductivity probe, a combo-well plate and a commercial DMM, is able to numerically display electrical conductivity of aqueous solutions ranging from non-conductive like deionized water as 0 to highly conductive such as 1M H₂SO₄ as 81, with a complete conductance calibrated at 100. The design allows digital display of conductivity measurement of aqueous solutions without the conventional reading unit of “μS/cm”.