Abstract
Both a ringed copper plate electrode and a carbon rod electrode were arranged in a Petri dish filled with the electrolyte solutions : 0.2M H_2SO_4, 0.2M Fe^<3+>+0.2M Fe^<2+>+0.2M H_2SO_4 and 0.2M Fe(CN)_6^<3->+0.2M Fe(CN)_6^<4->+0.2M H_2SO_4 aqueous solutions (1M=1 mol dm^<-3>). The Petri dish was placed on a permanent magnet. The geometrical arrangement is shown in Fig. 1. The vortex motion of the electrolyte solutions originated from the Lorentz's force was clearly observed as soon as the constant-current electrolysis was started. The magnitude of the vortex motion was estimated by the rotation rate (R) defined as the equation (2). The larger the electrolytic current was, the higher the rate became. The rate was in the order of Fe(CN)_6^<3->/Fe(CN)_6^<4->>Fe^<3+>/Fe^<2+>>H_2SO_4 systems and the order was probably due to the valence of the ionic species. In addition, the equation of motion was analyzed for the Fe^<2+> ion using a simplified model. The experiment was demonstrated in front of college students as estimators.
