The Construction and Characterization of a Conductivity Meter for Use in High School and Undergraduate Science Labs

The focus of this report is the design, construction and evaluation of a low-cost and portable conductivity meter. The instrument has facilitated the introduction and application of conductivity and resistivity to groups of middle school, high school, and undergraduate students. A series of laboratory experiments that demonstrate the utility and capabilities of the conductivity meter have also been developed and tested in multiple contexts. These lab experiments not only help characterize the conductivity meter, but also feature challenging and thought-provoking problems that allow students to realize the limitations of the instrument and place the data in context. The laboratory exercises a) investigate the effect of ion concentration, valence electrons, and temperature on conductivity measurements; b) conductometrically monitor and interpret a titration between a weak acid with a strong base; and c) determine the total dissolved solid (TDS) values for water collected at local creeks and dams on-site.