Sodium Carbonate, also known as soda ash or washing soda, is a strong alkali and a sodium salt of carbonic acid. It most commonly occurs as a crystalline heptahydrate in large transparent crystals, which readily effloresces, losing a large quantity of water to form a white powder, the monohydrate. Although this property does not interfere with the use of soda, since it is generally used in solution, efflorescence should be as far as possible avoided by keeping it in well-closed packages because effloresced soda dissolves more slowly than crystallizes since it has to combine with water before it can enter into solution.
Sodium carbonate is used in making lake pigments, such as madder lake: A very fine madder lake is obtained by dissolving 700 g of in 2 L of water and precipitating with 400 g of sodium carbonate, dissolved in 1,000 ml of water. The residue is washed with water five or six times. Then 300 g of madder dye or alizarin (20% paste), 150 g of Turkey-red oil or sulfonated castor oil, and 30 g of tannin are added, and the mixture is heated to 70° C. for half an hour. Another 200 g of Turkey-red oil is added, and the whole is boiled for 75 minutes. The pigment is then carefully washed and dried. In preparing this pigment, the solutions must be guarded from contact with iron. In drying lake pigments, the temperature should never exceed 60° C.
| Typical Properties | |
| Chemical Name: | Sodium Carbonate Heptahydrate |
| Chemical Formula: | Na2CO3·5H2O |
| CAS No.: | 497-19-8 |
| Mesh (%): | 100% |
| Color: | White powder |
Storage
Keep in a tightly closed container in a cool, dry, ventilated area. Protect against physical damage. Isolate from incompatible substances. When empty, containers of this material may be hazardous because they retain product residues (dust, solids); observe all warnings and precautions listed for the product.
Health and SafetyDANGER! MAY CAUSE EYE BURNS. HARMFUL IF SWALLOWED OR INHALED. CAUSES IRRITATION TO THE SKIN AND RESPIRATORY TRACT.
Wear impervious protective clothing, including boots, gloves, an apron, or coveralls, as appropriate, to prevent skin contact. Wear chemical safety goggles and a full-face shield where dusting or splashing of solutions is possible. Refer to the Safety Data Sheet.
Environmental HazardsThis product is toxic to aquatic organisms. If it is spilled, comply with Federal, State, and local regulations on reporting spills. For further details, refer to the Safety Sheet and labels.