Diffusion of H2SO4 in humidified nitrogen: Hydrated H2SO4

Citation
Dr. Hanson et F. Eisele, Diffusion of H2SO4 in humidified nitrogen: Hydrated H2SO4, J PHYS CH A, 104(8), 2000, pp. 1715-1719
Citations number
23
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Physical Chemistry/Chemical Physics
Journal title
JOURNAL OF PHYSICAL CHEMISTRY A
ISSN journal
1089-5639 → ACNP
Volume
104
Issue
8
Year of publication
2000
Pages
1715 - 1719
Database
ISI
SICI code
1089-5639(20000302)104:8<1715:DOHIHN>2.0.ZU;2-3
Abstract
First-order rate coefficients for the wall loss of H2SO4 were measured as a function of relative humidity in a high-pressure laminar flow tube in conj unction with chemical ionization mass spectrometry detection. The measureme nts yield a diffusion coefficient for H2SO4 vapor in N-2 at 298 K of 0.094 (+/-0.006) atm cm(2) s(-1) For relative humidities (RH) up to about 40%, th e measured first-order loss rates steadily decreased as the RH was increase d. The effective diffusion coefficient at 40% RH was similar to 20% less th an without H2O present. The measured loss rates were less dependent on wate r vapor for RH between 40 and 70%. We interpret these observations as due t o the addition of up to two H2O molecules to H2SO4, thus slowing the diffus ion rate to the wall. The results indicate that about half the H2SO4 molecu les are hydrated at similar to 8% RH and it is likely a second water molecu le interacts with this species at higher RH. Calculations of the decrease i n diffusivity of H2SO4 due to addition of water are consistent with the obs erved decreases.