1. What is the UNIFAC Activity Equation?

The UNIFAC (UNIQUAC Functional-group Activity Coefficients) method estimates activity coefficients in non-ideal mixtures using group contribution theory. It's widely used in chemical engineering for phase equilibrium calculations.

2. How Does the Calculator Work?

The calculator uses the UNIFAC activity equation:

Where:

• \( x_i \) — Mole fraction of component i (dimensionless)
• \( \gamma_i \) — Activity coefficient of component i (dimensionless)

Explanation: The equation calculates the dimensionless activity of a mixture by summing the product of mole fractions and natural logarithms of activity coefficients for each component.

3. Importance of Activity Calculation

Details: Activity coefficients are crucial for predicting phase behavior in non-ideal mixtures, designing separation processes, and modeling chemical reactions in solution.

4. Using the Calculator

Tips: Enter mole fractions (between 0 and 1) and activity coefficients (>0) for each component. The calculator supports binary mixtures (two components).

5. Frequently Asked Questions (FAQ)

Q1: What is the range of valid inputs?
A: Mole fractions must be between 0 and 1, and activity coefficients must be positive numbers.

Q2: Can I calculate for more than two components?
A: This calculator handles binary mixtures. For multicomponent systems, the equation would be extended with additional terms.

Q3: What are typical values for activity coefficients?
A: For ideal solutions, γ=1. Non-ideal solutions can have γ ranging from 0 to very large values depending on the system.

Q4: How accurate is UNIFAC?
A: UNIFAC is generally reliable for many common systems but may have limitations for complex molecules or extreme conditions.

Q5: What are the units of activity?
A: Activity is dimensionless, as it's a relative measure compared to a standard state.