THE CONVERSION OF SODIUM CHLORIDE TO HYDROGEN CHLORIDE IN THE ATMOSPHE

Abstract

A reaction route is suggested, based on experimental results, for the conversion of sodium chloride particles to gaseous hydrogen chloride in the atmosphere. The first step is the hydrolysis of nitrogen dioxide (NO₂) to form nitric acid (HNO₃) vapor. The second step is either adsorption on the relatively dry sodium chloride particles at relative humidities less than about 75 per cent or, at high relative humidities, solution in aqueous droplets containing sodium chloride. The third step is interaction of the nitric acid and sodium chloride and the fourth is desorption of the hydrogen chloride, either immediately following the reaction or during subsequent evaporation of the droplets. The results also indicate that the reaction between nitrogen dioxide and sodium chloride to form nitrosyl chloride (NOCl) and sodium nitrate (NaNO₃), often suggested as a possible primary step in the formation of chlorine or hydrogen chloride in the atmosphere, occurs at a negligible rate compared with the reaction described above.