Deliquescence is a property of a solid in which it:

Deliquescence is a property of certain solids in which the substance absorbs moisture from the atmosphere and eventually dissolves in the absorbed water to form a liquid solution. This behavior occurs because the solid has a high affinity for water molecules, and the amount of water it absorbs is enough to dissolve the solid completely.

Many salts and hygroscopic compounds exhibit deliquescence. Common examples include calcium chloride (CaCl₂), potassium hydroxide (KOH), and sodium hydroxide (NaOH). When left exposed to air, these salts absorb water vapor and gradually convert into a concentrated aqueous solution, unlike regular hygroscopic substances, which may absorb water but remain solid.

The difference between hygroscopicity and deliquescence is important. Hygroscopic solids absorb moisture but do not form a liquid, while deliquescent solids absorb enough moisture to dissolve themselves, forming a saturated solution.

Deliquescence depends on the vapor pressure of water over the solid and the surrounding humidity. A substance is deliquescent if its equilibrium vapor pressure is lower than the partial pressure of water vapor in the atmosphere. When the humidity is high enough, the solid continuously absorbs water until it liquefies.

Understanding deliquescence is important in inorganic chemistry and industrial applications. Deliquescent substances are used as drying agents, desiccants, and chemical reagents where water absorption is required. The property also explains storage precautions for certain salts, which must be kept in airtight containers to prevent them from turning liquid.

In summary, deliquescence is a unique property of certain solids where they absorb moisture from the air and convert into a liquid solution, illustrating the interaction between solids and water vapor in chemistry.