Ionization in reacting gases

Abstract

Ionization associated with the oxidation of ethyl alcohol in contact with electrodes.—Previous work had shown that various gaseous reactions are accompanied by ionization. The oxidation of ethyl alcohol was chosen because of its simplicity. Nitrogen carrying 3 cc of alcohol per minute and also dry oxygen at the rate of 200 cc per minute were sent into a reaction chamber between two concentric cylindrical electrodes. The currents were measured with an electrometer provided with a radioactive shunt. Although potential differences up to 1800 volts (2400 volts per cm) were used, the current was always proportional to the voltage, being evidently far from saturation. The variation with temperature, 150° to 330°C, was exponential, increasing in the case of gold electrodes 20 fold from 200° to 320°C. With Al electrodes the current was only 1/25th as great, and chemical analysis of the products of reaction indicated that the oxidation was also greatly reduced. The results show that the reaction occurs at the electrode surfaces, the rate depending on the material and on the temperature, and that both positive and negative ions are produced. The absence of saturation is probably due to the ions being formed so close to the surface. Copper electrodes gave anomalous results, a negative Cu electrode behaving like Au while a positive Cu electrode behaved like Al. A soft glass electrode behaved like gold, except that the logarithmic increase with temperature was twice as fast for the negative as for the positive electrode.

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