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Sodium acetate column. A supersaturated solution of sodium acetate being poured from a bottle onto a table. As the liquid hits tiny 'seed' crystals on the surface, it instantly crystallises and forms a solid column. Sodium acetate trihydrate dissolves in its own water of crystallisation when heated above 58C. If this is allowed to cool slowly to room temperature, the solution becomes supersaturated. In contact with a suitable condensation nucleus, such as a crystal or even dust, it instantly starts to recrystallise. This is a highly exothermic process and is used in hand warmers and similar heating pads.
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