Introduction A variety of electrochemical sensors are used for the measurement of pH, dissolved oxygen, concentrations of a variety of ions, and oxidation-reduction potentials. Applications vary widely. These include monitoring the neutralization of waste water containing sulfides, cyanides, chromates, nitrites, or organic waste and controlling the addition of oxidants such as ozone or chlorine to drinking water, swimming pools, or cooling towers. They are used to determine the concentrations of metal ions in solutions, natural waters, and waste waters and to determine the endpoint of titrations. Hospitals use them to monitor oxygen-rich atmospheres and divers use them to monitor the oxygen content of diving gases.
Electrochemical sensors contain a reference electrode and a sensing electrode.
The sensors produce a voltage that changes as the concentration of the sensed chemical species changes. In our experiment the copper metal in the known copper sulfate solution is the reference electrode whose potential does not change. The silver metal in the titration solution is the sensing electrode whose potential will change as the titration proceeds. The Experiment Building the Silver Ion Sensor 1. Completely wet a piece of filter paper with KNO 3 solution and place half of this paper strip inside a six-inch glass test tube and the other half into a clean dry 250 mL beaker.