| 摘要 |
PURPOSE:To avoid fall in accuracy due to electrode pollution by immersing a pair of electrodes in two solution baths having the same iodine ion concentration or bromine ion concentration but different iodine concentration or bromine concentration. CONSTITUTION:A chemical solution in a vessel 8, for instance, KI, passes through the continuous pores of a porous ceramic 6 and leaks out by a minute amount into the water to be tested in a water testing tank 1. Most part of the residual chlorine has become HOCl or OCl<->, but the KI that eluted reacts with HOCl to free I2. The anode 4 that is immersed in the water gives the balanced potential E1 that corresponds to the concentrations of I2 and I<-> respectively, and the cathode 5 gives the potential E2 corresponding to I<-> in the vessel 7, because the water level of the chemical solution is made higher than the level of the water to be tested, which prevents intrusion of I2. The potential difference E= E1-E2 corresponds to the concentration of the residual chlorine. |
