Fick's First Law Calculator
Calculation Result:
What is Fick's First Law of Diffusion?
Fick's First Law describes the steady-state diffusion process where the flux of a substance goes from regions of high concentration to regions of low concentration. In simple terms, it measures how fast a material moves through a medium based on the concentration gradient.
The mathematical formula is expressed as: J = -D * (ΔC / Δx)
- J: Diffusion Flux (amount of substance per unit area per unit time).
- D: Diffusion Coefficient or Diffusivity (reflects how easily the particles move).
- ΔC: The change in concentration (C₂ - C₁).
- Δx: The distance or thickness over which diffusion occurs.
How to Use This Calculator
To calculate the diffusion flux using this tool, follow these steps:
- Enter the Diffusion Coefficient (D). This value is usually specific to the materials involved and the temperature.
- Input the Concentration at Position 1 (C₁) and Position 2 (C₂). Ensure you use consistent units (e.g., kg/m³ or mol/m³).
- Enter the Distance (Δx) between these two concentration points.
- Click "Calculate" to find the flux (J).
Why is the result sometimes negative?
In the formula J = -D(dc/dx), the negative sign indicates the direction of diffusion. Diffusion naturally occurs down the concentration gradient (from high to low concentration). If your calculated flux is positive, it means the substance is moving in the direction of the distance measured. If it is negative, it is moving in the opposite direction.
Frequently Asked Questions (FAQs)
Consistency is key. If D is in m²/s and concentration is in kg/m³, the flux (J) will be in kg/(m²·s). If you use moles, the flux will be in mol/(m²·s).
No, Fick's First Law applies to steady-state conditions where the concentration gradient does not change over time. For non-steady state, Fick's Second Law is used.