Deliquescence

Deliquescence occurs when a solid absorbs atmospheric water vapor until it dissolves in the absorbed water, forming a liquid solution.

Deliquescence relative humidity: The equilibrium humidity above which a crystalline salt absorbs water and forms a saturated solution. It marks the humidity threshold at which deliquescence begins for a given salt.
Relative humidity: The ratio of water vapor pressure in air to the saturation vapor pressure at the same temperature. It is the atmospheric quantity compared with a salt’s deliquescence threshold.
Hygroscopic salts: Ionic compounds that readily take up water vapor from the surrounding air. Some salts absorb enough water to deliquesce at ordinary atmospheric humidities.
Sodium chloride: An ionic compound composed of sodium and chloride ions, commonly known as table salt. Its deliquescence near 75% relative humidity is a familiar reference point.
Water activity: A measure of water’s escaping tendency in a material, defined relative to pure water at the same temperature. It links the solution’s equilibrium vapor pressure to the surrounding humidity.
Water vapor: Water in its gaseous state, present in air as an invisible gas. It supplies the molecules that a deliquescent solid absorbs.
Desiccant: A material used to remove water vapor from an enclosed environment. Desiccants manage moisture, while deliquescent substances may themselves become wet or liquid.
Calcium chloride: An ionic calcium salt that is highly soluble in water and strongly absorbs atmospheric moisture. It deliquesces at much lower humidity than sodium chloride.
Hygroscopicity: The tendency of a substance to absorb moisture from its surroundings. Deliquescence is a strong outcome of moisture uptake, ending in a liquid solution.
Aqueous solution: A homogeneous mixture in which water is the solvent. This is the liquid phase produced when absorbed water dissolves the solid.

Linked from 15 pages