when trying to purify aspirin, why would i have to add hot water to the crystals that are formed, and then recool the crystals? what does this do to the crystals?

thermal heating takes place in different forms of kinesthetic energy.

When purifying aspirin, adding hot water to the crystals followed by recooling serves two purposes:

1. Dissolving impurities: When crystals are formed, they can trap certain impurities within their structure. By adding hot water, the crystals are partially dissolved, allowing the impurities to dissolve and separate from the aspirin molecules.

2. Recrystallization: By subsequently cooling the solution, the aspirin molecules reassemble and reform new, purer crystals. During this process, the impurities remain in the liquid phase or form separate crystals, which can then be removed.

To understand the impact on the crystals, we need to consider some fundamental principles of solubility. When a solute (aspirin in this case) is dissolved in a solvent (hot water), it creates a solution. The solubility of most solid compounds generally increases with temperature, meaning more solute can dissolve in hot water compared to cold water.

When the solution cools down, the solubility of the solute decreases, resulting in precipitation of the dissolved solute, forming new crystals. However, the impurities, being less soluble, are either left behind in the liquid or form separate impure crystals.

Overall, this process of dissolving the crystals in hot water and then recrystallizing them upon cooling helps to purify aspirin by separating impurities from the desired compound.