Gaseous product identification and kinetic analysis of solid/liquid reactions between alkali chlorides with nitric acid solutions
Presentation Type
Poster
Presentation Type
Submission
Keywords
Sea salt, smog, chlorine, nitrosyl chloride, nitric acid
Department
Chemistry
Major
Chemistry
Abstract
Sea spray aerosol, tiny droplets formed through breaking waves, is a large source of natural environmental particles. When these droplets are kicked up into the atmosphere, pollutant gases can transform the sea spray into an acidic medium from which chlorine-containing pollutant gases Cl2 and ClNO form. These chlorine-containing gases have the potential, in the presence of sunlight, to efficiently initiate a cascade of events leading to tropospheric (ground level) ozone, the key player in smog. Ozone is well-known to adversely impact human health.
This laboratory study examined the mechanism by which chlorine-containing product gases (Cl2, ClNO, ClNO2 and HCl) form when components of sea salt are highly acidified by nitric acid. The gases were identified spectroscopically and quantified using multicomponent Beer’s Law analyses incorporating single wavelength UV-Vis and integrated IR absorption cross-sections from primary literature. Evolution of the product gases were followed in situ using an all-glass reactor fitted inside spectrophotometers. Temporal studies are consistent with a two-step mechanism with the major products Cl2 and ClNO formed in nearly equimolar amounts, varying according to the enhanced solubility of ClNO in the reaction solutions. This study has implications for the role of active chlorine in tropospheric smog chemistry.
Faculty Mentor
Jane Ganske
Funding Source or Research Program
Academic Year Undergraduate Research Initiative, John Stauffer Charitable Trust, Summer Undergraduate Research Program
Location
Waves Cafeteria
Start Date
22-3-2024 1:30 PM
End Date
22-3-2024 2:30 PM
Gaseous product identification and kinetic analysis of solid/liquid reactions between alkali chlorides with nitric acid solutions
Waves Cafeteria
Sea spray aerosol, tiny droplets formed through breaking waves, is a large source of natural environmental particles. When these droplets are kicked up into the atmosphere, pollutant gases can transform the sea spray into an acidic medium from which chlorine-containing pollutant gases Cl2 and ClNO form. These chlorine-containing gases have the potential, in the presence of sunlight, to efficiently initiate a cascade of events leading to tropospheric (ground level) ozone, the key player in smog. Ozone is well-known to adversely impact human health.
This laboratory study examined the mechanism by which chlorine-containing product gases (Cl2, ClNO, ClNO2 and HCl) form when components of sea salt are highly acidified by nitric acid. The gases were identified spectroscopically and quantified using multicomponent Beer’s Law analyses incorporating single wavelength UV-Vis and integrated IR absorption cross-sections from primary literature. Evolution of the product gases were followed in situ using an all-glass reactor fitted inside spectrophotometers. Temporal studies are consistent with a two-step mechanism with the major products Cl2 and ClNO formed in nearly equimolar amounts, varying according to the enhanced solubility of ClNO in the reaction solutions. This study has implications for the role of active chlorine in tropospheric smog chemistry.