What Is Nucleation?
Nucleation is a physical reaction which occurs when components in a solution start to precipitate out, forming nuclei which attract more precipitate. In a simple example of nucleation, supersaturated sugar water is used to make rock candy, with the sugar crystals nucleating and growing into crystals. This physical reaction is the basis for a variety of manufacturing processes and interesting natural phenomena. In homogeneous nucleation, the solution is totally uniform, and the process occurs spontaneously, usually in response to something like a change in pressure or temperature. Heterogeneous nucleation involves a solution which is mixed in nature. Nucleation tends to occur much more quickly in such mixtures. As an example of the difference between heterogeneous and homogeneous nucleation, purified water freezes at a lower temperature than conventional water, because the purified water lacks small particles which can be used as “seeds” to start the nucleation process. Typically, once
