ACS Analytical Chemistry Practice Exam

Reference electrodes provide a stable, known potential that stays essentially constant as current flows in the measurement. In potentiometric experiments, you determine the potential of the working electrode relative to this reference. Because the reference potential is fixed, any change observed at the working electrode directly reflects the analyte’s influence, allowing accurate determination of the unknown potential. The measured cell potential is the difference between the working and reference electrodes, so a steady reference potential makes it possible to relate the reading to the analyte. In practice, reference electrodes are designed to be non-polarizable, with common systems like Ag/AgCl or SCE. The other options aren’t about providing a stable reference potential: measuring pH is done with a pH-sensitive electrode, driving reactions requires applying current through working and counter electrodes, and viscosity isn’t determined from electrochemical potentials.