Sodium carbonate (Na2CO3), is commonly known as soda, crystal soda, soda ash and washing soda; its chemical formula is Na2CO3. Sodium carbonate containing ten crystal waters is clear crystal. Crystal water is not stable and easy to be weathered and become white powers. Na2CO3 is a kind of strong electrolyte, and has the general properties of salt and thermal stability. Besides, it is readily soluble in water and its water solution is alkaline.

　　Under normal temperature, sodium carbonate is white powders or particles. Besides, it is odorless, water absorbing, and a kind of strong alkali-weak acid salt. When it is exposed to the air, it can absorb water of 1mol/L (about 15%). It will degrade and effervesce when contacting with acid. It is soluble to water (3.5 portions at room temperature and 2.2 portions at 35℃) and glycerol, and slightly soluble to absolute ethyl alcohol. Its water solution is strongly alkaline, and its pH is 11.6. Its relative density is (25℃) 2.53; its melting point is 851℃; its medium lethal dose (30 days) (mice, abdomen) is 116.6mg/kg. It is irritating, and is formed through the chemical reaction of sodium hydroxide and carbonic acid. Moreover, sodium carbonate degrades at 2,132K.

　　Solubility

　　Sodium carbonate is soluble to water and glycerol, and at 20℃, 20g sodium carbonate can dissolve in 100g water. At 35.4 ℃, the solubility reaches the largest, and 49.7g sodium carbonate can dissolve in 100g water. Besides, it is slightly soluble to absolute ethyl alcohol, and not soluble to propanol ethyl carbinol. As a kind of strong alkali salt, sodium carbonate will hydrolyze (hydrolysis of sodium carbonate will generate sodium bicarbonate and sodium hydroxide) when it is dissolved in water, making the solution alkaline with certain corrosivity. When it contacts with acids, double decomposition reaction ( ) will occur and corresponding salts and carbon dioxide will be generated and released respectively.

　　Stability

　　Sodium carbonate has strong stability, and can degrade under high temperature to generate sodium oxide and carbon dioxide. When it is exposed to air for a long time, it will absorb the moisture and carbon dioxide in the air to generate sodium bicarbonate and then become caked mass itself. It has strong hygroscopicity; it is easy to become caked mass which will not degrade under high temperature. Moreover, there are three kinds of sodium carbonates containing crystal water: Na2CO3·H2O, Na2CO3·7H2O and Na2CO3·10H2O.