Wilke Chang Equation For Liquid Phase Diffusivity Calculator

Wilke Chang Equation:

\[ D_{AB} = \frac{1.173 \times 10^{-16} \times (\phi_B \times M_b)^{1/2} \times T}{\mu \times (V_m/1000)^{0.6}} \]

Association Factor (φB):

Molecular Weight B (Mb):

kg/mol

Temperature of Gas (T):

Dynamic Viscosity of Liquid (μ):

Pa·s

Molar Volume of Liquid (Vm):

m³/mol

Diffusion Coefficient (DAB):

m²/s

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is the Wilke Chang Equation?

The Wilke Chang Equation is a semi-empirical correlation used to estimate the diffusion coefficient of a solute in a dilute solution. It's particularly useful for predicting liquid-phase diffusivities in various chemical engineering applications.

2. How Does the Calculator Work?

The calculator uses the Wilke Chang equation:

\[ D_{AB} = \frac{1.173 \times 10^{-16} \times (\phi_B \times M_b)^{1/2} \times T}{\mu \times (V_m/1000)^{0.6}} \]

Where:

\( D_{AB} \) — Diffusion coefficient (m²/s)
\( \phi_B \) — Association factor (dimensionless)
\( M_b \) — Molecular weight of solvent B (kg/mol)
\( T \) — Temperature (K)
\( \mu \) — Dynamic viscosity of liquid (Pa·s)
\( V_m \) — Molar volume of liquid (m³/mol)

Explanation: The equation accounts for the effects of temperature, viscosity, molecular size, and solvent association on the diffusion process.

3. Importance of Diffusion Coefficient Calculation

Details: Accurate diffusion coefficient estimation is crucial for designing separation processes, predicting mass transfer rates, and modeling chemical reactions in liquid systems.

4. Using the Calculator

Tips: Enter all values with appropriate units. The association factor is typically 1.0 for non-associated solvents, 1.5 for ethanol, 1.9 for methanol, and 2.6 for water.

5. Frequently Asked Questions (FAQ)

Q1: What is the typical range for diffusion coefficients in liquids?
A: Diffusion coefficients in liquids typically range from 10⁻⁹ to 10⁻¹⁰ m²/s, which is about 10,000 times smaller than in gases.

Q2: How accurate is the Wilke Chang equation?
A: The equation provides reasonable estimates (within 10-15% error) for many systems but may be less accurate for highly associated solvents or large molecules.

Q3: When should I use this equation?
A: It's most appropriate for dilute solutions of non-electrolytes in common solvents at moderate temperatures.

Q4: What are the limitations of this equation?
A: It doesn't work well for electrolytes, concentrated solutions, or systems with strong specific interactions.

Q5: Are there alternative methods for estimating diffusion coefficients?
A: Yes, other methods include the Stokes-Einstein equation for large spherical molecules and various empirical correlations for specific systems.