Question

Ficks' law of diffusion states that mass flux per unit area of a component is directly proportional to its ________.

• A. Velocity gradient
• B. Temperature gradient
• C. Concentration gradient
• D. pH gradient

Hint:

Remember the analogies for transport phenomena:

Mass Transfer (Fick's Law): Flux \(\propto\) \textbf{Concentration Gradient}
Heat Transfer (Fourier's Law): Flux \(\propto\) \textbf{Temperature Gradient}
Momentum Transfer (Newton's Law): Flux \(\propto\) \textbf{Velocity Gradient} \end{itemize}

Answer 1

The Correct Option is C

Step 1: State Fick's First Law of Diffusion. The law describes the relationship between the flux of a component and its concentration profile.

Step 2: Write the mathematical expression for the law. \[ J = -D \frac{dC}{dx} \] Where:


\(J\) is the mass flux (mass flowing per unit area per unit time).
\(D\) is the diffusion coefficient (a proportionality constant).
\(\frac{dC}{dx}\) is the concentration gradient, which is the change in concentration (dC) over a change in position (dx). \end{itemize} The law explicitly states that the flux is directly proportional to the concentration gradient. The negative sign indicates that diffusion occurs from a region of higher concentration to a region of lower concentration.