How Do Crystals Grow?
ES0506  What Controls Crystal Growth?

One way crystals form is out of solutions that contain dissolved material. Consider a spoonful of table salt dissolved in a glass of warm water as an example.

LuAnn Dahlman, TERC

When water begins evaporating from the solution, the amount of salt in the glass remains the same. At some point, there is simply not enough water left to keep the sodium and chlorine ions from joining together, so salt crystals will begin to form.

If the water evaporates very slowly from the solution, over many weeks, relatively few crystals will get started, and these will have time to grow fairly large before the water is gone.

If water evaporates from the solution more quickly, more crystals get started, but they don't have time to grow as large.

The example described above shows that evaporation rate is one variable that controls crystal growth. Consider what other conditions might affect crystal growth. Do you think changing the temperature, pressure, or amount of dissolved material in a solution would affect crystal growth?


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