Explain why the dissolution of a crystalline particle in a solution can be speeded up by (a) stirring the solution and (b) by crushing the particle, from a mass transfer perspective.

Rate of solubility of solids in liquids depend on these factors:

Stirring the solution : This process brings fresh solvent particles to come in contact with the solute particles and hence stirring increases the rate of dissolution.

Crushing the particle: If the solute particles is present in smaller size, more it can be dissolved because decreasing the size increases the surface area of the solute particles and thus more of them can come in contact with the solvent. Hence, the dissolution increases.

Thus both stirring the solution and crushing the particles increases the dissolution by ensuring more contact of solute with the solvent.