Define Deliquescent crystal with example.
Answers
Deliquescence refers to the property of a substance to absorb water from the air to dissolve itself and form an aqueous solution. Materials with this property are termed deliquescent. Deliquescent materials are a class of hygroscopic substances. Other types hygroscopic materials may absorb water, yet not dissolve. In order to be deliquescent, a substance must both absorb a large amount of water and be sufficiently soluble to dissolve in it.
Examples of Deliquescent Substances
Most deliquescent substances are salts. Examples include sodium hydroxide, potassium hydroxide, ammonium chloride, gold(III) chloride, sodium nitrate, and calcium chloride. While table salt or sodium chloride (NaCl) may be deliquescent if the particles are small and the humidity is very high, salt is usually considered to be hygroscopic.
Because of their affinity for water, deliquescent substances find use as desiccants. They may be used to remove excess water from sulfuric and phosphoric acids. In the chemical industry, deliquescent chemicals are used to remove water from chemical reactions.
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Deliquescence, the process by which a substance absorbs moisture from the atmosphere until it dissolves in the absorbed water and forms a solution. Deliquescence occurs when the vapour pressure of the solution that is formed is less than the partial pressure of water vapour in the air. All soluble salts will deliquesce if the air is sufficiently humid. A substance that absorbs moisture from the air but not necessarily to the point of dissolution is called hygroscopic.
The effectiveness of calcined calcium chloride in settling road dust is a result of its deliquescence. When spread in the form of a powder or flakes, it absorbs more than its own weight of water and forms a liquid that keeps the road wet. See also efflorescence.