Hygroscopic substances are those substances that absorb water vapour from the air. The process is called Hygroscopicity.

Some Hygroscopic Substances

Concentrated sulphuric acid H2SO4 Magnesium chloride MgCl2
Anhydrous calcium chloride CaCl2 Ferric Chloride FeCl3
Calcium oxide CaO Phosphorus pentoxide P4O10
Solid Sodium hydroxide NaOH Calcium nitrate Ca(NO3)2
Solid potassium hydroxide KOH Copper nitrate Cu(NO3)2

Certain hygroscopic substances, not only absorb moisture from the air, but also dissolve themselves in that moisture, undergoing a change of state. Such substances are called deliquescent substances. The process is called Deliquescence.

No comments: