Activity Coefficient Calculator

How to Use This Calculator

1. Enter the mole fraction of the solute (x₁) in the solution (a value between 0 and 1).
2. Input the temperature of the solution in Kelvin (K). Ensure the temperature is above absolute zero (0 K).
3. Provide the pressure of the solution in bar. A typical atmospheric pressure is 1 bar (101.325 kPa).
4. Enter the density of the solution in kg/m³. This helps in determining the activity coefficient based on solution composition.
5. Click the "Calculate" button to compute the activity coefficient.
6. The calculator will display the activity coefficient (γ₁) based on the input parameters.

Working Principle

The activity coefficient (γ₁) is a measure of how the real behavior of a solute in a solution deviates from ideal behavior. It is defined as the ratio of the activity of the solute to its mole fraction:

γ₁ = φ₁ / x₁

Where φ₁ is the normalization factor that depends on the mole fraction of the solute (x₁). This calculator uses a simplified formula for demonstration purposes:

φ₁ = (1 - x₁)² + 2x₁(1 - x₁)

In real applications, the activity coefficient may be calculated using more complex models such as the Margules equation, UNIQUAC model, or other empirical correlations that account for non-ideal interactions between solute and solvent molecules.

Applications

Activity coefficients are important in:

• Chemical engineering for process design and optimization
• Pharmaceutical industry for drug solubility studies
• Environmental science for pollutant behavior in water
• Food science for understanding solute-solvent interactions

Limitations

This calculator provides a simplified calculation for educational purposes. For accurate results in real-world applications, consider using more sophisticated models and experimental data where available.