Related Experiment Video
Updated: May 27, 2026
12:11
Computation of Atmospheric Concentrations of Molecular Clusters from ab initio Thermochemistry
Published on: April 8, 2020
Evaporation rate of nucleating clusters
1Department of Physics, University of Helsinki, P.O. Box 64, FIN-00014 Helsinki, Finland. evgeni.zapadinsky@helsinki.fi
The Journal of Chemical Physics
|November 25, 2011
Summary
The Becker-Döring model for vapor-liquid nucleation was enhanced to include all cluster configurations. This study reveals a correction factor to nucleation rates due to differing evaporation rates in steady-state and equilibrium conditions.
Area of Science:
- Physical Chemistry
- Chemical Engineering
- Thermodynamics
Background:
- The Becker-Döring model is standard for vapor-liquid nucleation studies.
- It typically assumes identical evaporation rates in balanced and unbalanced steady states.
- This assumption simplifies calculations but may lack precision.
Purpose of the Study:
- To extend the Becker-Döring model by incorporating master equations for all cluster configurations.
- To investigate the validity of assuming identical evaporation rates in equilibrium and unbalanced steady states.
- To derive a correction factor for nucleation rates based on differing evaporation dynamics.
Main Methods:
- Extension of the Becker-Döring kinetic scheme to include master equations for all cluster configurations.
- Comparison of balanced steady-state (equilibrium) and unbalanced steady-state solutions of kinetic equations.
- Analysis of evaporation rates and cluster size distributions in different steady states.
Main Results:
- Evaporation rates are not identical in equilibrium and unbalanced steady-state cases.
- The ratio of limited-definition n-clusters to total n-clusters differs between equilibrium and unbalanced states.
- A correction factor, approximately 10⁻¹, is introduced for nucleation rates, potentially lower with carrier gas equilibration.
Conclusions:
- The assumption of identical evaporation rates in the Becker-Döring model is inaccurate.
- A refined nucleation rate calculation is possible by accounting for differing evaporation dynamics.
- The developed approach enables further refinement using Monte Carlo and molecular dynamics simulations.
Related Concept Videos
02:39Phase Transitions: Vaporization and Condensation
The physical form of a substance changes on changing its temperature. For example, raising the temperature of a liquid causes the liquid to vaporize (convert into vapor). The process is called vaporization—a surface phenomenon. Vaporization occurs when the thermal motion of the molecules overcome the intermolecular forces, and the molecules (at the surface) escape into the gaseous state. When a liquid vaporizes in a closed container, gas molecules cannot escape. As these gas phase molecules...
01:18Vaporization
The physical form of a substance changes by changing its temperature. For example, raising the temperature of a liquid causes the liquid to vaporize (convert into vapor). The process is called vaporization—a surface phenomenon. For vaporization to occur, kinetic energy must be greater than the intermolecular forces that keep molecules bonded. The amount of energy needed to vaporize a quantity of liquid at a given pressure and a constant temperature is called the heat of vaporization. When...
01:10Recrystallization: Solid–Solution Equilibria
Recrystallization is a purification technique used to separate impurities from solid compounds. In this technique, no chemical reactions occur. Instead, it exploits physical properties only, specifically, the solubility differences between the desired compound and impurities, either at a single temperature or at different temperatures, and under other selected conditions. The solid-solution equilibrium (solubility equilibrium) of each component in the solution represents a binary phase...
01:16Precipitate Formation and Particle Size Control
In precipitation gravimetry, the precipitating agent should react specifically or selectively with the analyte. While a specific reagent reacts with the analyte alone, a selective reagent can react with a limited number of chemical species.
The obtained precipitate should be either a pure substance of known composition or easily converted to one by a simple process, such as ignition or drying. In addition, the precipitate should be insoluble and easily filterable. In general, filterability...
The obtained precipitate should be either a pure substance of known composition or easily converted to one by a simple process, such as ignition or drying. In addition, the precipitate should be insoluble and easily filterable. In general, filterability...
01:01Distillation: Vapor–Liquid Equilibria
Distillation is a separation technique that takes advantage of the boiling point properties of disparate elements in a mixture. To perform distillation, we begin by heating a miscible mixture of two liquids with a significant difference in boiling points (at least 20°C). As the solution heats up and reaches the bubble point of the more volatile component, some molecules of the more volatile component transition into the gas phase and travel upward into the condenser, which is a glass tube with...
00:52Washing, Drying, and Ignition of Precipitates
After filtration, the precipitate is washed to remove coprecipitated impurities and any remaining mother liquor. Colloidal precipitates, such as silver chloride, are washed with an electrolyte (such as dilute nitric acid) to prevent the peptization of the precipitate. In the case of slightly soluble precipitates, the wash solution contains a common ion to reduce solubility. Lead sulfate, which is slightly soluble in water, is washed with dilute sulfuric acid. Similarly, wash solutions may be...