1. What is the Diffusion Coefficient?

The diffusion coefficient (D) is a proportionality constant that relates the molar flux due to molecular diffusion to the concentration gradient. It describes how quickly particles spread out from an area of high concentration to an area of low concentration.

2. How Does the Calculator Work?

The calculator uses the diffusion coefficient formula:

Where:

• \( D \) — Diffusion coefficient (m²/s)
• \( \lambda \) — Mean free path (m)
• \( v \) — Velocity of particles (m/s)

Explanation: The equation shows that diffusion is faster when particles travel further between collisions (larger λ) and move faster (larger v).

3. Importance of Diffusion Coefficient

Details: The diffusion coefficient is crucial in fields like chemistry, physics, and engineering for understanding transport phenomena, predicting reaction rates, and designing separation processes.

4. Using the Calculator

Tips: Enter mean free path in meters and velocity in meters per second. Both values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is the typical range for diffusion coefficients?
A: In gases: ~10⁻⁵ m²/s; in liquids: ~10⁻⁹ m²/s; in solids: ~10⁻¹⁴ m²/s.

Q2: How does temperature affect diffusion coefficient?
A: Diffusion coefficient increases with temperature according to the Arrhenius equation.

Q3: What is the relationship to Fick's laws?
A: The diffusion coefficient appears in Fick's first and second laws of diffusion.

Q4: What factors affect mean free path?
A: Pressure (inverse relationship), temperature (direct relationship), and molecular size.

Q5: How is this different from mass transfer coefficient?
A: Diffusion coefficient is a material property, while mass transfer coefficient depends on flow conditions.