Sodium carbonate decahydrate, commonly known as washing soda or soda crystals, is an inorganic salt with the chemical formula Na₂CO₃·10H₂O. It appears as colorless, transparent crystals or a white crystalline powder. This compound is the fully hydrated form of sodium carbonate and is highly soluble in water, producing an alkaline solution. Its primary industrial applications are extensive. It serves as a crucial raw material and processing aid in the manufacture of glass, detergents, and soaps. In water treatment, it is used for pH adjustment and water softening. It also finds use in the textile industry for scouring and bleaching, in the paper and pulp industry, and in various chemical synthesis processes as a mild base and source of carbonate ions. Due to its deliquescent nature, the decahydrate form is less common in industrial settings than the anhydrous or monohydrate forms, which are more stable for storage and transport. From a chemical synthesis perspective, it functions as a fundamental inorganic base and a source of carbonate anions. It is employed in various reactions, including hydrolysis, neutralization, and precipitation. Handling requires standard precautions for alkaline materials, as it can cause irritation to skin, eyes, and the respiratory tract.