Rate of Diffusion Calculator

Fick's First Law of Diffusion:

\[ \text{rate} = D \times A \times \frac{\Delta C}{L} \]

Diffusion Coefficient (D):

m²/s

Cross-sectional Area (A):

m²

Concentration Difference (ΔC):

mol/m³

Thickness (L):

Rate of Diffusion:

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1. What is Fick's First Law of Diffusion?

Fick's First Law describes the diffusion of substances across a concentration gradient. It states that the rate of diffusion is proportional to the concentration gradient and the cross-sectional area, and inversely proportional to the distance over which diffusion occurs.

2. How Does the Calculator Work?

The calculator uses Fick's First Law of Diffusion:

\[ \text{rate} = D \times A \times \frac{\Delta C}{L} \]

Where:

\( D \) — Diffusion coefficient (m²/s)
\( A \) — Cross-sectional area (m²)
\( \Delta C \) — Concentration difference (mol/m³)
\( L \) — Thickness/distance (m)

Explanation: The equation calculates how quickly a substance diffuses through a medium based on its properties and the conditions.

3. Importance of Diffusion Rate Calculation

Details: Understanding diffusion rates is crucial in fields like chemistry, biology, materials science, and engineering for processes like gas exchange, drug delivery, and material fabrication.

4. Using the Calculator

Tips: Enter all values in SI units. The diffusion coefficient (D) is typically very small (e.g., ~10⁻⁹ m²/s for small molecules in water). All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What affects the diffusion coefficient (D)?
A: Temperature, size of diffusing particles, and properties of the medium (viscosity, porosity).

Q2: What are typical values for diffusion coefficients?
A: In water at 25°C: small ions ~10⁻⁹ m²/s, proteins ~10⁻¹¹ m²/s. In air, gases are ~10⁻⁵ m²/s.

Q3: When is Fick's Law not applicable?
A: In turbulent flow, with very large concentration gradients, or when chemical reactions are occurring.

Q4: How does temperature affect diffusion rate?
A: Higher temperature increases D and thus increases diffusion rate (approximately doubles per 10°C rise).

Q5: What's the difference between diffusion and osmosis?
A: Diffusion is movement of any particles down concentration gradient; osmosis specifically refers to solvent (usually water) movement across a semipermeable membrane.