Which of the following best describes the effect of particle size on the rate at which a solid substance dissolves in a solvent?

• A. Smaller particle size increases the rate of dissolution because it increases the surface area exposed to the solvent.
• B. Smaller particle size decreases the rate of dissolution because it reduces the number of particles available.
• C. Particle size has no effect on the rate of dissolution of a solid.
• D. Larger particle size increases the rate of dissolution because it allows more collisions with solvent molecules.

Answer: (A)

Verified step by step guidance

1. Understand that the rate of dissolution depends on how quickly solvent molecules can interact with the surface of the solid particles.
2. Recall that smaller particle size means the solid is broken into more pieces, which increases the total surface area exposed to the solvent.
3. Recognize that an increased surface area allows more solvent molecules to collide with the solid simultaneously, speeding up the dissolution process.
4. Contrast this with larger particles, which have less surface area relative to their volume, resulting in fewer collisions and a slower dissolution rate.
5. Conclude that smaller particle size increases the rate of dissolution because it increases the surface area exposed to the solvent.