Why does stirring a solution help a solid dissolve faster?
We have all seen it in the lab and at home. Put a teaspoon of sugar in your tea or coffee, and sometimes, if you don't stir it well, you find a residue of sugar in the bottom of your mug. Stirring mechanically agitates the solute, and brings fresh unsaturated solvent into contact with the solid solute. Of course, heating will also get the solute into solution but this is a thermodynamic effect rather than a kinetic effect.