Na2CO37H2O

Sodium carbonate heptahydrate, with the chemical formula Na2CO3·7H2O, is a specific hydrated form of sodium carbonate. Sodium carbonate, also known as soda ash or washing soda, is an alkali metal salt of carbonic acid. In its heptahydrate form, seven molecules of water are associated with each formula unit of sodium carbonate. This compound typically appears as efflorescent crystalline solids, meaning they tend to lose water of hydration when exposed to air. It is less common than the decahydrate form (Na2CO3·10H2O) or the anhydrous form (Na2CO3). The properties of sodium carbonate heptahydrate are influenced by the presence of the bound water molecules, affecting its solubility and melting point compared to the anhydrous salt. It is generally soluble in water, and its solutions are alkaline due to hydrolysis. While sodium carbonate in its various hydrated and anhydrous forms has numerous industrial applications, including in glass manufacturing, detergents, and chemical production, the heptahydrate form is less frequently encountered in large-scale industrial processes compared to its more stable counterparts. Care should be taken when handling hydrated sodium carbonates as they can cause irritation to skin and eyes.