Activity Coefficient Calculator
Calculate activity coefficients (γ₁, γ₂) for binary non-electrolyte liquid mixtures using Margules 1-parameter (2-suffix), Margules 2-parameter (3-suffix), or van Laar models (VLE).
Use the Activity Coefficient Calculator
Inputs
Calculates activity coefficients for binary non-electrolyte liquid mixtures (VLE). Not for aqueous electrolyte ionic strength (Debye–Hückel).
x₂ = 1 − x₁ is computed automatically.
Enter values and click Calculate.
Activity Coefficients
Activities
Thermodynamic Properties
Common Binary Mixture Constants
Values are for the van Laar / 2-parameter Margules model at approximately 25 °C unless noted. Component 1 is listed first.
| Component 1 | Component 2 | A₁₂ | A₂₁ | Model |
|---|---|---|---|---|
| Ethanol | Water | 1.6798 | 0.9227 | Van Laar |
| Acetone | Chloroform | −0.8206 | −1.3376 | Van Laar |
| Ethanol | Benzene | 1.7500 | 1.7500 | Margules (sym.) |
| Acetone | Water | 0.5990 | 0.7480 | Van Laar |
| n-Hexane | Ethanol | 2.0800 | 1.9200 | Van Laar |
| Benzene | Toluene | 0.4200 | 0.4200 | Margules (sym.) |
| Methanol | Water | 1.5240 | 1.6348 | Van Laar |
Click any row to load its constants into the calculator. A₁₂ = A₂₁ for symmetric systems (use Margules 1-parameter with A = A₁₂).
Summary
Calculate activity coefficients (γ₁, γ₂) for binary non-electrolyte liquid mixtures using Margules 1-parameter (2-suffix), Margules 2-parameter (3-suffix), or van Laar models (VLE).
How it works
- Select a model: Margules 1-parameter (2-suffix symmetric), Margules 2-parameter (3-suffix asymmetric), or van Laar.
- Enter mole fraction x₁ (0 to 1). x₂ is computed automatically as 1 − x₁.
- Enter the required model constant(s): A for 1-parameter, or A₁₂ and A₂₁ for 2-parameter / van Laar.
- Click Calculate to get γ₁, γ₂, activities a₁ and a₂, and excess Gibbs energy gᴱ/RT.
- Compare your result against the reference table of common binary mixture constants.
Use cases
- Verify non-ideality of ethanol-water or acetone-chloroform mixtures in VLE calculations.
- Determine activity coefficients for distillation column design.
- Estimate excess Gibbs energy for thermodynamic modeling of solution behavior.
- Check whether a mixture exhibits positive (γ > 1) or negative (γ < 1) deviation from Raoult's law.
- Validate experimental data against Margules or van Laar model predictions.