scholarly journals Molecular properties affecting the hydration of acid-base clusters

2021 ◽  
Author(s):  
Nanna Myllys ◽  
Deanna Myers ◽  
Sabrina Chee ◽  
James N. Smith
Keyword(s):  
Chemical Reactions ◽  
Aerosol Particles ◽  
Cluster Formation ◽  
Molecular Properties ◽  
Acid Base

In the atmosphere, water in all phases is ubiquitous and plays important roles in catalyzing atmospheric chemical reactions, participating in cluster formation and affecting the composition of aerosol particles. Direct...

scholarly journals Density changes of aerosol particles as a result of chemical reaction

2004 ◽  
Vol 4 (5) ◽  
pp. 6431-6472 ◽  
Author(s):  
Y. Katrib ◽  
S. T. Martin ◽  
Y. Rudich ◽  
P. Davidovits ◽  
J. T. Jayne ◽  
...  
Keyword(s):  
Oleic Acid ◽  
Oxygen Content ◽  
Chemical Reactions ◽  
Aerosol Particles ◽  
Ozone Exposure ◽  
Spherical Particles ◽  
Aerodynamic Diameter ◽  
Layer Density ◽  
Aerosol Mass ◽  
Mobility Diameter

Abstract. This paper introduces the capability to study simultaneously changes in the density, the chemical composition, the mobility diameter, the aerodynamic diameter, and the layer thickness of multi-layered aerosol particles as they are being altered by heterogeneous chemical reactions. A vaporization-condensation method is used to generate aerosol particles composed of oleic acid outer layers of 2 to 30 nm on 101-nm polystyrene latex cores. The layer density is modified by reaction of oleic acid with ozone for variable exposure times. For increasing ozone exposure, the mobility diameter decreases while the vacuum aerodynamic diameter increases, which, for spherical particles, implies that particle density increases. The aerosol particles are confirmed as spherical based upon the small divergence of the particle beam in the aerosol mass spectrometer. The particle and layer densities are calculated by two independent methods, namely one based on the measured aerodynamic and mobility diameters and the other based on the measured mobility diameter and particle mass. The uncertainty estimates for density calculated by the second method are two to three times greater than those of the first method. Both methods indicate that the layer density increases from 0.89 to 1.12 g·cm−3 with increasing ozone exposure. Aerosol mass spectrometry shows that, concomitant with the increase in the layer density, the oxygen content of the reacted layer increases. Even after all of the oleic acid has reacted, the layer density and the oxygen content continue to increase slowly with prolonged ozone exposure, a finding which indicates continued chemical reactions of the organic products either with ozone or with themselves. The results of this paper provide new insights into the complex changes occurring for atmospheric particles during the aging processes caused by gas-phase oxidants.

Physicochemical and Photosorption Properties of Oxygen-Containing Calcium Compounds – Components of Troposferic Aerosol

2015 ◽  
Vol 1085 ◽  
pp. 124-129
Author(s):  
Elena B. Daibova ◽  
Tamara S. Minakova ◽  
Valeriy S. Zakharenko ◽  
Natalia I. Kosova ◽  
Irina A. Kurzina ◽  
...  
Keyword(s):  
Aerosol Particles ◽  
Interaction Process ◽  
Lewis Base ◽  
Toxic Substances ◽  
Effective Quantum Yield ◽  
Acid Base ◽  
Indicator Method ◽  
A Value ◽  
Calcium Compounds ◽  
Ph Metry

The Importance of this Paper is Determined by the Research of Conditions of Photosorption Processes Occurance on the Surface of Aerosol Particles Resulting in the Removal of Toxic Substances from the Atmosphere. Acid-Base Properties of Oxygen-Containing Calcium Compounds being Components of Troposphere Aerosol Particles were Studied by Methods of Ph-Metry and Hammet’s Indicators. the Basic Properties of the Investigated Compounds Surfaces are Predominant Ones: рНiis of Calcium Oxide and Hydroxide has a Value of 9.3 – 9.5, and that for Carbonate and Calcite Equals to 12.3-12.4. Indicator Method Distinguishes Three Areas of Spectrum Corresponding to Lewis Base, and Brensted Neutral and Basic Centers. the Intencity of Peaks is much Higher for Ca(OH)2 and CaO. the Interaction Process of Halogen-Containing Organic Compounds (Freons: 134a, 22 and 12) with Calcium Carbonate Surface under Illumination in Conditions close to Tropospheric Conditions was Studied. it is Shown that the Interaction is the Destructive Photosorption of Freons (134a or 22). the Spectral Dependence of Effective Quantum Yield of Destructive Photosorption is Determined. as a Result of the Interaction Calcium Fluoride and Calcium Chloride are Formed at the Surface.

scholarly journals TO THE ISSUE OF FINDING THE STOICHIOMETRIC COEFFICIENTS IN THE CHEMICAL REACTIONS

2021 ◽  
Vol 2 ◽  
pp. 19-48
Author(s):  
Jekaterina Aleksejeva ◽  
Sharif Guseynov
Keyword(s):  
Chemical Reactions ◽  
Redox Reactions ◽  
Algebraic Equations ◽  
Computer Implementation ◽  
Acid Base ◽  
Linear Algebraic Equations ◽  
Ill Posed ◽  
Computational Errors

In the present paper, on the basis of the theory of inverse and ill-posed problems, an algorithm is proposed that allows to unambiguously determine the stoichiometric coefficients in the equations of chemical reactions of any type, including redox reactions and acid-base reactions, and, regardless of whether the constructed system of linear algebraic equations for the desired stoichiometric coefficients is underdetermined (i.e. there are fewer equations than unknowns) or overdetermined (i.e. there are more equations than unknowns). The proposed algorithm is a regularized algorithm (according to Tikhonov), which ensures that, in a computer implementation, possible computational errors will not make the comprised system of linear algebraic equations to be incapable of solving.

Evolution of boundary-layer aerosol particles due to in-cloud chemical reactions during the 2nd Lagrangian experiment of ACE-2

Tellus B ◽  
2000 ◽  
Vol 52 (2) ◽  
pp. 452-462 ◽  
Author(s):  
Anthony J. Dore ◽  
Douglas W. Johnson ◽  
Simon R. Osborne ◽  
Thomas W. Choularton ◽  
Keith N. Bower ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Chemical Reactions ◽  
Aerosol Particles

A new classification scheme for teaching reaction types in general chemistry

2019 ◽  
Vol 0 (0) ◽  
Author(s):  
Bin Wang
Keyword(s):  
General Chemistry ◽  
Chemical Reactions ◽  
Redox Reactions ◽  
Classification Scheme ◽  
College Level ◽  
New Classification ◽  
Acid Base ◽  
Oxidation Reduction ◽  
Upper Level ◽  
Nuanced Understanding

AbstractGeneral chemistry is a freshman-level class required for most science majors and pre-professional undergraduates. A variety of concepts are introduced in this course; among them, chemical reactions are fundamental, but remain a central topic. The author compared 10 textbooks widely used for college-level general chemistry courses. They all cover the three major classes of chemical reactions: precipitation reactions, acid-base reactions, and oxidation-reduction (redox) reactions. However, significant differences in the way these textbooks present the material may cause confusion and misunderstanding for students, including when they move to upper-level courses. The author suggests a modified reaction classification scheme for general chemistry courses, which will provide students a more complete and nuanced understanding of chemical reactions.

scholarly journals Do atmospheric aerosols form glasses?

2008 ◽  
Vol 8 (3) ◽  
pp. 9263-9321 ◽  
Author(s):  
B. Zobrist ◽  
C. Marcolli ◽  
D. A. Pedernera ◽  
T. Koop
Keyword(s):  
Water Activity ◽  
Water Uptake ◽  
Chemical Reactions ◽  
Aerosol Particles ◽  
Laboratory Data ◽  
Dicarboxylic Acids ◽  
Ice Nucleation ◽  
Water Soluble ◽  
Transition Temperatures ◽  
Upper Troposphere

Abstract. A new process is presented by which water-soluble organics might influence ice nucleation, ice growth, chemical reactions and water uptake of aerosols in the upper troposphere: the formation of glassy aerosol particles. Glasses are disordered amorphous (non-crystalline) solids that form when a liquid is cooled without crystallization until the viscosity increases exponentially and molecular diffusion practically ceases. The glass transition temperatures, Tg, homogeneous ice nucleation temperatures, Thom, and ice melting temperatures, Tm, of various aqueous inorganic, organic and multi-component solutions are investigated with a differential scanning calorimeter. The investigated solutes are: various polyols, glucose, raffinose, levoglucosan, an aromatic compound, sulfuric acid, ammonium bisulphate and mixtures of dicarboxylic acids (M5), of dicarboxylic acids and ammonium sulphate (M5AS), of two polyols, of glucose and ammonium nitrate, and of raffinose and M5AS. The results indicate that aqueous solutions of the investigated inorganic solutes show Tg-values that are too low to be of atmospheric importance. In contrast, aqueous organic and multi-component solutions readily form glasses at low but atmospherically relevant temperatures (≤230 K). To apply the laboratory data to the atmospheric situation, the measured phase transition temperatures were transformed from a concentration to a water activity scale by extrapolating water activities determined between 252 K and 313 K to lower temperatures. The obtained state diagrams reveal that the higher the molar mass of the aqueous organic or multi-component solutes, the higher Tg of their respective solutions at a given water activity. To a lesser extent, Tg also depends on the hydrophilicity of the organic solutes. Therefore, aerosol particles containing larger and more hydrophobic organic molecules (≳150 g mol-1) are more likely to form glasses at intermediate to high relative humidities in the upper troposphere. Our results suggest that the water uptake of aerosols, heterogeneous chemical reactions in aerosol particles, as well as ice nucleation and ice crystal growth can be significantly impeded or even completely inhibited in organic-enriched aerosols at upper tropospheric temperatures with implications for cirrus cloud formation and upper tropospheric relative humidity.

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