- When liquid turns into solid a nucleus is required. Is the same requirement present for solid-liquid (melting)?
- Do condensation also require nucleation sites like in freezing? When I look at descriptions for phase equilibrium or condensation, the vapour phase just “goes” into the liquid phase. If I cool a closed container with no nucleation sites where liquid-vapour are in equilibrium, should I expect the vapour be supersaturated (kind of like supercooling a liquid)?
To answer your second question, yes, condensation typically requires nucleation. Supersaturated vapours like the one you describe are the basis of the cloud chambers that used to be used as particle detectors. The energetic particles passing through the vapor would ionize molecules, and these ions would act as nucleation sites.