The H{sub 2}SO{sub 4} vapor pressure of sulfate solutions approximating atmospheric aerosols
- Univ. of Minnesota, Minneapolis, MN (United States)
- National Center for Atmospheric Research, Boulder, CO (United States); and others
Atmospheric aerosols frequently contain sulfates and ammonium. Modeling aerosol nucleation and growth thus requires thermodynamic data on the sulfuric acid-water-ammonium sulfate system. A key component of the latter is information on sulfuric acid H{sub 2}SO{sub 4} vapor pressures for H{sub 2}SO{sub 4}-H{sub 2}O- (NH{sub 4}){sub 2}SO{sub 4} mixtures that approximate those found in atmospheric particles. Using a flow tube system and a chemical ionization mass spectrometer, measurements of H{sub 2}SO{sub 4} vapor pressure were performed for sulfuric acid solutions between 63 and 73 wt%. The results were in general agreement with theoretical predictions. Sulfuric acid vapor pressures were also measured over pure ammonium sulfate solids at low relative humidities and partially neutralized solutions whose [NH{sub 4}{sup +}]/[SO{sub 4}{sup =}] ratio ranged from 0.125 to 2. The results suggest that H{sub 2}SO{sub 4} vapor pressures fall off rapidly as the ratio exceeds 0.5. The data lend support to an aerosol formation mechanism that involves ammonia at the outset of cluster nucleation.
- OSTI ID:
- 166560
- Report Number(s):
- CONF-9510126--
- Country of Publication:
- United States
- Language:
- English
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