Question

41 multiple choice 1 point which of the following statements is correct regarding net diffusion? the rate is independent of temperature. molecular weight of a substance does not affect the rate. the greater the concentration gradient, the faster the rate. the lower the temperature, the faster the rate.

Explanation:

• Temperature affects the kinetic energy of molecules. Higher temperature means more kinetic energy, so diffusion rate is temperature - dependent. So the statement "The rate is independent of temperature" is wrong.
• Molecular weight affects the speed of molecules. Lighter molecules move faster, so molecular weight affects the diffusion rate. So the statement "Molecular weight of a substance does not affect the rate" is wrong.
• According to Fick's law of diffusion ($J=-D\frac{dC}{dx}$, where $J$ is the diffusion flux, $D$ is the diffusion coefficient, and $\frac{dC}{dx}$ is the concentration gradient), the greater the concentration gradient ($\frac{dC}{dx}$), the greater the diffusion flux ($J$), which means a faster rate.
• Lower temperature means less kinetic energy for molecules, so the diffusion rate is slower. So the statement "The lower the temperature, the faster the rate" is wrong.

Answer:

The greater the concentration gradient, the faster the rate.