Which description best characterizes diffusion in a solid?

Which description best characterizes diffusion in a solid?

• A. Very slow
• B. No diffusion
• C. Very fast
• D. Diffusion is the same as in liquids

Answer: (A)

Diffusion in a solid happens as atoms or ions move by jumping between lattice sites or moving through defects, but the solid’s tightly packed structure leaves little room for movement. The particles are held in fixed positions most of the time, so getting from high concentration to low concentration requires overcoming energy barriers and finding rare vacancies or defects to hop into. That makes the rate of diffusion in solids extremely slow, especially at room temperature. That’s why “very slow” is the best description. Diffusion does occur in solids, it’s not zero, but it’s not comparable to how fast it happens in liquids or gases, where particles move much more freely. It isn’t correct to say it’s very fast or the same as in liquids.

Diffusion in a solid happens as atoms or ions move by jumping between lattice sites or moving through defects, but the solid’s tightly packed structure leaves little room for movement. The particles are held in fixed positions most of the time, so getting from high concentration to low concentration requires overcoming energy barriers and finding rare vacancies or defects to hop into. That makes the rate of diffusion in solids extremely slow, especially at room temperature.

That’s why “very slow” is the best description. Diffusion does occur in solids, it’s not zero, but it’s not comparable to how fast it happens in liquids or gases, where particles move much more freely. It isn’t correct to say it’s very fast or the same as in liquids.