Sodium nitrate is hygroscopic colorless transparent triangular crystal. Decompose when heated to 380 ℃. It is very soluble in water and liquid ammonia, soluble in methanol and ethanol, very slightly soluble in acetone and slightly soluble in glycerol. When dissolved in water, it absorbs heat, the solution becomes cold, and the aqueous solution is neutral. It is obtained by absorbing nitrogen oxides from industrial alkali solution, evaporation and crystallization. Sodium nitrate is used to make nitric acid and sodium nitrate additive, as ingredients in glass, match, enamel or ceramic industry, fertilizer, catalyst in sulfuric acid industry, etc.