The scientific name of soda is sodium bicarbonate, and its appearance is white crystalline powder or opaque monoclinic fine crystals. It is an inorganic salt with strong alkali and weak acid properties, weakly alkaline, soluble in water and insoluble in ethanol. The solubility in water is 7.8g( 18℃), 16.0g(60℃), the density is 2.20g/cm3, the specific gravity is 2.208, and the refractive index is α:1.465; β: 1.498; γ: 1.504, with standard entropy of 24.4 j/(mol k).
The heat of formation is 229.3kJ/mol, the heat of solution is 4.33kJ/mol, and the specific heat (CP) is 20.89 j/(mol c) (22℃). Sodium bicarbonate is stable at room temperature, easily decomposed when heated, and rapidly decomposed above 50℃. The molecular formula is NaHCO? It is an inorganic compound, a white crystalline powder, odorless, salty and soluble in water.
Preparation method of sodium bicarbonate:
1, waste lye recovery method
In the process of soda ash production, the furnace gas produced by soda ash calciner still contains more alkali powder after cyclone separation. Recovery of furnace gas with hot alkali makes alkali powder dissolve in alkali solution. In the process of circulating dissolution, part of the alkali liquor is sent to the ammonia distillation tower, and the ammonia in the hot alkali liquor is evaporated, and the alkali liquor is further concentrated as the alkali liquor raw material for producing baking soda. The mixed gas of ammonia, carbon dioxide and water from the top of ammonia distillation tower enters the original furnace gas cooling tower.
In baking soda production, the separated and dehydrated mother liquor is used for hot alkali liquor circulation to dissolve and recover alkali powder from furnace gas, which constitutes a production process circulation.
2, trona processing method
Taking trona as raw material, due to the high impurity content, it is necessary to strictly control the temperature, concentration and cycle times of the mother liquor when preparing the alkali liquor. The total salt content in the mother liquor should be greater than 240 g/L, the alkali liquor concentration after alkalization should be greater than 150g/L, the sodium chloride should be less than 50g/L, and the sodium sulfate should be less than 90g/L. The obtained alkali liquor is filtered to remove residues, and then carbonized with carbon dioxide to generate sodium bicarbonate crystals. After washing and dehydration, the washing liquid can be returned to alkalization or discharged, and the crystals are dried to prepare the finished product of sodium bicarbonate.
3. Laboratory preparation
Sodium bicarbonate can be prepared by the reaction of sodium carbonate aqueous solution with carbon dioxide in the laboratory.