PHYSICAL-CHEMISTRY OF THE H2SO4 H2O BINARY-SYSTEM AT LOW-TEMPERATURES- STRATOSPHERIC IMPLICATIONS/

Laboratory experiments have been carried out to investigate the physic al chemistry of the H2SO4/H2O binary system under conditions character istic of the stratosphere. Water vapor pressures of sulfuric acid solu tions (20-70 wt %) and of liquid-solid and solid-solid phase coexisten ce systems have been measured by mass spectrometry at temperatures bet ween 190 and 240 K. Infrared spectra of the liquid. supercooled liquid , and crystalline hydrates of this system have also been investigated. The results indicate that some of the hydrates of sulfuric acid (i.e. , H2SO4-4H2O, H2SO4.6.5H2O, and H2SO4.8H2O) may form and persist under the temperature and water partial pressure conditions typical of the high-latitude stratosphere.