| This first series of diagrams shows what happens if you let a crystallization proceed slowly: first by setting the flask at room temperature undisturbed until crystals form, and then carefully on ice. The yellow triangles are an impurity in the hot solution of orange hexagons. If the solution is allowed to cool slowly, the impurities may sit down briefly in the growing crystal lattice, but they soon leave as a compound with a more suitable geometry comes in to take their place. Suitable hexagons stay more readily in the growing lattice, and eventually pure crystals of orange hexagons are formed. | |||||||||
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| This second series of diagrams shows what happens if you cool the solution too quickly. The yellow triangle impurities are trapped inside the crystals being formed by the orange hexagons, thus, the crystals isolated are impure. | ||||||||||
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| Note that slow crystallization gives larger crystals than this series of fast crystallization. Small crystals have a large surface area to volume ratio and impurities are located on the surface of the crystals as well as trapped inside the matrix. | ||||||||||
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