How does the Clark polarographic O2 electrode function?

Question

a. It measures the magnetic properties of O2 versus N2.
b. It measures the electrical potential across a Wheatstone bridge.
c. It uses O2 to produce a reduc-tion-oxidation reaction.
d. It measures the comparative cooling effect on a heated wire.

Answer 1

ANS: C
This system typically consists of a platinum cathode and a silver-silver chloride anode (Figure 19-1). Oxygen molecules diffuse through the sensor membrane into the electrolyte, where a po-larizing voltage causes electron flow between the anode and cathode. While silver is oxidized at the anode, the flow of electrons reduces oxygen (and water) to hydroxyl ions (OH−) at the cath-ode. The more O2 molecules that are reduced, the greater is the electron flow across the poles (current). The resulting change in current is proportional to the PO2, with its value displayed on a galvanometer, calibrated in percent oxygen.