The action of nitric acid on alkali halides releases chlorine-containing gases which significantly impact the oxidizing capacity of the atmosphere and are also key players in corrosion chemistry. We report here the identification and quantification of product gases evolved during solid/liquid reactions of NaCl, KCl and LiCl with aqueous nitric acid solutions. Utilizing multicomponent Beer’s law analyses incorporating single wavelength UV-Vis absorption cross-sections and integrated IR absorption cross-sections from the primary literature, gaseous products of these reactions were quantified and include Cl2, ClNO and HCl. Evolution of product gases from the heterogeneous reactions was followed in situ using a glass/Teflon reactor and flow system fitted inside the spectrophotometer’s sampling compartment. Temporal studies are consistent with a two-step reaction mechanism with the major products Cl2 and ClNO formed in approximately equimolar amounts, modified by the enhanced solubility of ClNO in the reaction solution. As acidification of aging chloride-containing aerosols in the polluted troposphere is a source of active chlorine, the atmospheric relevance of these studies is discussed.

Product gas identification and quantitation in the heterogeneous reactions between alkali chlorides and nitric acid solutions: An in situ spectroscopic analysis

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