precipitation (redirected from Precipitaiton)

precipitation, in chemistry

precipitation, in chemistry, a process in which a solid is separated from a suspension, sol, or solution. In a suspension such as sand in water the solid spontaneously precipitates (settles out) on standing. In a sol the particles are precipitated by coagulation. A solute (dissolved substance) may be precipitated from a solution by several means. A solution of salt may be concentrated by evaporation until the salt crystallizes. When a saturated solution of sugar is cooled, sugar crystals form. The addition of a solution of silver nitrate to a solution containing chloride ions results in the formation of insoluble silver chloride: AgNO₃+Cl⁻→NO₃⁻+AgCl↓. In each case the precipitate formed may settle out spontaneously or may be collected by filtration or centrifugation. It is often difficult to obtain a pure substance by a single precipitation, and a substance may be further purified by reprecipitation after it has been redissolved. The term precipitation is also applied to the separation of particles of a solid or liquid suspended in a gas.

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precipitation, in meteorology

precipitation, in meteorology, condensed moisture that falls to the surface of the earth in the form of rain, sleet, snow, hail, frost, or dew.

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precipitation

All liquid and solid water particles that fall from clouds and reach the ground, including drizzle, rain, snow, ice crystals, and hail. The essential difference between a precipitation particle and a cloud particle is size; an average raindrop has a mass equivalent to that of about one million cloud droplets. Precipitation elements (ice crystals or droplets that form around soluble particles such as salt) form directly from the vapour state and get larger through collision and coalescence. Eventually they become large enough to respond to gravity, and they fall to the ground.

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precipitation

1. Meteorol

a. rain, snow, sleet, dew, etc., formed by condensation of water vapour in the atmosphere

b. the deposition of these on the earth's surface

c. the amount precipitated

2. the production or formation of a chemical precipitate

3. Spiritualism the appearance of a spirit in bodily form; materialization

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precipitation [prə‚sip·ə′tā·shən]

(chemistry)

The process of producing a separable solid phase within a liquid medium; represents the formation of a new condensed phase, such as a vapor or gas condensing to liquid droplets; a new solid phase gradually precipitates within a solid alloy as a result of slow, inner chemical reaction; in analytical chemistry, precipitation is used to separate a solid phase in an aqueous solution.

(immunology)

Aggregation of soluble antigen by an antibody.

(meteorology)

Any or all of the forms of water particles, whether liquid or solid, that fall from the atmosphere and reach the ground.

The amount, usually expressed in inches of liquid water depth, of the water substance that has fallen at a given point over a specified period of time.