MCQ Detailed View

Deliquescence is a physical process where certain substances absorb moisture from the air until they dissolve in the absorbed water and form a solution. These substances are called deliquescent substances. They are often salts or compounds that are highly soluble in water and can draw water vapor directly from the atmosphere.

Common examples of deliquescent substances include calcium chloride (CaCl₂), sodium hydroxide (NaOH), and potassium hydroxide (KOH). When exposed to humid air, these substances do not stay in solid form. Instead, they become wet and eventually dissolve completely in the absorbed water.

The process of deliquescence depends on the humidity level of the surrounding environment. If the relative humidity is higher than a substance’s critical point, the substance will begin to absorb moisture and deliquesce.

Efflorescence is the opposite of deliquescence. It occurs when a substance loses water to the air and forms a dry, powdery surface. An example is sodium sulfate decahydrate (Na₂SO₄·10H₂O), which can lose water and become dry in the open air.

Dehydrogenation is a chemical process in which hydrogen atoms are removed from a molecule. It is unrelated to atmospheric moisture.

Desalination is a physical separation process used to remove salt from saline water. It is used in water purification and does not involve atmospheric absorption.

Deliquescence is important in storage and packaging. Deliquescent materials require airtight containers to prevent them from turning into liquid. This property is studied in physical chemistry under the topic of hygroscopic and deliquescent behaviors of solids.