Activity Coefficient Model: Van Laar

The model is described in: J.J. Van Laar, The Vapor Pressure of Binary Mixtures, Z. Phys. Chem., 1910, Vol. 72, p. 723.

G^EX/(R×T) = a₁×a₂×x₁×x₂/(a₁×x₁ + a₂×x₂) Parameters determined in TDE are a₁ and a₂ .

For the symmetric form of the model, a₁ = a₂.

Temperature dependencies for activity-coefficient model parameters are expressed with: TDE-TSeries1.

Details of the model implementation in TDE, including ThermoML-Equation representation are available. (See the ThermoML web site for details of this IUPAC communication standard.)

• Purpose of TDE
• Critically Evaluated Properties
• Pure Component Properties
• Binary Mixture Properties
• Ternary Mixture Properties
• Reaction Properties
• Material Stream Properties
• How to do EVALUATIONS
• Evaluation for PURES
• Compound Selection (Pures)
• Add User Data (Pures)
• "Superstructure" Component Search
• Evaluation for BINARIES
• Component Selection (Binary)
• Component 1 Selection
• Component 2 Selection
• Add User Data (Binary)
• Evaluation for TERNARIES
• Component Selection (Ternary)
• Add User Data (Ternary)
• Evaluation for REACTION
• Reaction Selection
• Participant Selection
• Formation Properties Evaluation
• Evaluation for MATERIAL STREAM
• Component Selection (Stream)
• Apply/Fit AC Model to Sub-Systems
• Add Composition
• Add Property Calculation
• Explore Calculation Results
• Save Results
• The Main Screen Menus
• File Menu
• View Menu
• Action Menu
• Equation of State (EOS) Menu
• Mixture Menu
• Product Design Menu
• Experiment Planning Menu
• Updates Menu
• The Main Screen Window
• Navigation Tree (Pures)
• Compound
• Property Name/Phase Formats
• Expt and Predicted Data
• Reaction Data
• Default Equations
• Property Consistency
• Evaluated Data
• Evaluated Enthalpy of Formation
• Alternative Equations
• Equations of State
• Calculated with EOS
• Navigation Tree (Mixtures)
• Components of Binary Mixture
• Expt and Predicted Data
• VLE Data Summary View (Binary)
• VLE Datasets & Consistency Tests
• VLE Datasets
• VLE Consistency Tests
• VLE Data Summary View (Ternary)
• LLE Data Summary View (Binary)
• LLE Data Summary View (Ternary)
• Expt Data (Display only)
• Single Property Equations
• Calc w/ Single-Property Eq's
• Multi-Property Equations (Binaries)
• Multi-Property Equations (Ternaries)
• VLE Model/Data Comps (Ternary)
• LLE Model/Data Comps (Ternary)
• Calc w/ Multi-Property Eq's
• Navigation Tree (Reactions)
• Properties of Participants
• Expt and Predicted Data
• Consistency with Participant Data
• Evaluated Reaction Data
• Navigation Tree (Material Stream)
• Components
• Binary Sub-Systems (A + B)
• Composition Number
• Add Composition
• Calculation Number
• Add Calculation
• Property Nomenclature (Mixtures)
• Property Nomenclature: SLE
• Property Nomenclature: LLE
• Property Nomenclature: VLE
• Data Table Features
• Data Tables (General Info)
• Bibliographic Info (Data Source)
• Sort Data
• Select Data Set (or Single Value)
• Plot Data
• VLE Data Summary (Binaries)
• VLE Data Summary (Ternaries)
• LLE Data Summary (Binaries)
• LLE Data Summary (Ternaries)
• Flawed Data
• Plot Features
• Plot Legend (Colors)
• Plots: General Info (Pures)
• Right-Click Features (Pures)
• Plots: General Info (Binary)
• Right Click Features: (Binary)
• Single-Property Equations (Pures)
• Vapor Pressure
• Sublimation Pressure
• Crystal-Liquid boundary
• Density (sat liquid)
• Density (sat vapor)
• Density (liquid- 1 phase)
• Density (gas- 1 phase)
• Enthalpy of Vaporization
• Enthalpy of Sublimation
• Heat Capacity (Csat- crystal)
• Heat Capacity (Csat- liquid)
• Heat Capacity (Ideal Gas)
• Entropy & Enthalpy, derived (crystal)
• Entropy & Enthalpy, derived (liquid)
• Speed of Sound (liquid)
• Speed of Sound (gas)
• Refractive Index (liquid)
• Surface Tension
• Viscosity (sat liquid)
• Viscosity (gas)
• Thermal Conductivity (sat liquid)
• Thermal Conductivity (gas)
• Single-Property Equations (Binaries)
• Single-Property Equations (Ternaries)
• EOS Fitting (Pures)
• EOS Fitting Process (Pures)
• EOS: Equations Supported (Pures)
• Span-Wagner
• PC-SAFT
• Modified Sanchez-Lacombe
• Peng-Robinson (Original)
• Peng-Robinson (Twu)
• Peng-Robinson (Mathias-Copeman)
• Peng-Robinson (SRW)
• REFPROP (Read Only)
• TDE Generated (Read Only)
• Activity Coeff. Model Fitting (Mixtures)
• AC Model Fitting (Binaries)
• Model Fitting Control Center
• Model Configuration Form
• Activity Coeff. Models (Binaries)
• UNIFAC Prediction (Original)
• UNIFAC Prediction (NIST-KT)
• UNIFAC Prediction (NIST-Modified)
• NIST-COSMO-SAC Prediction
• NRTL
• Redlich-Kister
• UNIQUAC
• Van Laar
• Wilson
• Activity Coeff. Model Calcs. (Ternaries)
• Gas-Phase Models (Mixtures)
• Special Displays: VLE-LLE-SLE
• VLE Consistency Tests (Binary)
• VLE Isotherm Plot (Binary)
• VLE Isobar Plot (Binary)
• VLE Plot for Peng-Robinson EOS
• VLE Isopleth Plot for P-R EOS
• Azeotropic Data (Binary)
• LLE Diagram (Binary)
• SLE Diagram (Binary)
• LLE Diagram (Ternary)
• VLE Gas Composition (Ternary)
• Uncertainties
• Uncertainties in Tables & Plots
• Uncertainty Definitions
• Output Files & Formats
• Eq Parameter Definitions
• Eq Parameter O/P
• TDE-SOURCE Data Archive
• Web Updates
• Database Version Control
• Show TDE-SOURCE Version
• Addition of User Data
• Structure Drawing
• Prediction Methods (Pures)
• Formation Reaction Properties
• Properties of Elements
• NIST/REFPROP Database in TDE
• Product Design
• Pure Compound
• Solvent for Solid
• Specify Solute
• Enter Temperature
• Add Solvent Efficiency
• Add Solvent Property
• Specify Compound Class
• Select Database
• Select Model Basis
• Search and Results
• Explore Results
• Save Results
• Selective Solvent for Solid Mixture
• Specify Solute & Contaminant
• Enter Temperature
• Add Solvent Efficiency
• Add Solvent Property
• Specify Compound Class
• Select Database
• Select Model Basis
• Search and Results
• Explore Results
• Save Results
• Solvent for Extraction
• Specify Solute & Carrier
• Enter Temperature
• Add Solvent Efficiency
• Add Solvent Property
• Specify Compound Class
• Select Database
• Select Model Basis
• Search and Results
• Explore Results
• Save Results
• Experiment Planning
• Evaluate Measurement (Pure)
• Evaluate Measurement (Binary)
• Recommend Measurements (Pure)
• UNIFAC Extension
• ThermoML- IUPAC Standard
• References
• Glossary
• FAQ

The TRC Group is part of the Applied Chemicals and Materials Division in NIST's Material Measurement Laboratory
The National Institute of Standards and Technology is an agency of the U.S. Department of Commerce

©2017 copyright by the US Secretary of Commerce on behalf of the United States of America. All rights reserved.