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The precipitation of a compound may occur when its concentration exceeds its solubility. This can be due to temperature changes, solvent evaporation, or by mixing solvents. Precipitation occurs more rapidly from a strongly supersaturated solution. The formation of a precipitate can be caused by a chemical reaction.
Precipitation occurs when a portion of the atmosphere becomes saturated with water vapor (reaching 100% relative humidity), so that the water condenses and "precipitates" or falls. Thus, fog and mist are not precipitation; their water vapor does not condense sufficiently to precipitate, so fog and mist do not fall.
The term precipitation is normally reserved for describing a phase change from a colloid dispersion to a solid (precipitate) when it is subjected to a perturbation. [19] Aggregation causes sedimentation or creaming, therefore the colloid is unstable: if either of these processes occur the colloid will no longer be a suspension.
In chemistry, the common-ion effect refers to the decrease in solubility of an ionic precipitate by the addition to the solution of a soluble compound with an ion in common with the precipitate. [1] This behaviour is a consequence of Le Chatelier's principle for the equilibrium reaction of the ionic association / dissociation .
The pI value can affect the solubility of a molecule at a given pH. Such molecules have minimum solubility in water or salt solutions at the pH that corresponds to their pI and often precipitate out of solution. Biological amphoteric molecules such as proteins contain both acidic and basic functional groups. Amino acids that make up proteins ...
Salting out is typically used to precipitate large biomolecules, such as proteins or DNA. [2] Because the salt concentration needed for a given protein to precipitate out of the solution differs from protein to protein, a specific salt concentration can be used to precipitate a target protein. This process is also used to concentrate dilute ...
Sleet and freezing rain occur by a similar process, but are different forms of precipitation. Both are most common in the winter. Sleet occurs when snowflakes melt into a raindrop in a wedge of ...
Evaporite minerals start to precipitate when their concentration in water reaches such a level that they can no longer exist as solutes. The minerals precipitate out of solution in the reverse order of their solubilities, such that the order of precipitation from sea water is: Calcite (CaCO 3) and dolomite (CaMg(CO 3) 2)