Sodium silicate (Na2SiO3) is a compound made of sodium, silicon, and oxygen. It has many uses, including as a detergent, adhesive, and in the production of silica gel.
| IUPAC Name | Sodium metasilicate |
| Molecular Formula | Na2SiO3 |
| CAS Number | 6834-92-0 |
| Synonyms | Water glass, liquid glass, soluble glass, sodium orthosilicate, sodium silicate glass, sodium metasilicate |
| InChI | InChI=1S/2Na.O3Si/c;;1-4(2)3/q2*+1;-2 |
Sodium Silicate Properties
Sodium Silicate Formula
The formula of sodium silicate is Na2SiO3, which indicates that each unit of the compound contains two sodium atoms, one silicon atom, and three oxygen atoms. Sodium silicate is also known by other formulas such as Na2O·nSiO2 and Na2SiO4, depending on the number of SiO2 units in the polymeric anion. The formula of sodium silicate is crucial in understanding its chemical properties and in calculating its molar mass and molecular weight.
Sodium Silicate Molar Mass
Na2SiO3 has a molar mass of approximately 122.06 g/mol. This is calculated by adding the atomic masses of sodium (22.99 g/mol), silicon (28.09 g/mol), and oxygen (16.00 g/mol) present in the compound. Molar mass is a crucial property for Na2SiO3 as it helps in determining the amount of the compound required in a reaction.
Sodium Silicate Boiling Point
The boiling point of Na2SiO3 is not a single value but rather a range of temperatures. Na2SiO3 solutions, which are commonly used in industrial applications, have a boiling range of 100-110 °C. The boiling point of Na2SiO3 depends on factors such as its concentration, purity, and the presence of impurities.
Sodium Silicate Melting Point
Na2SiO3 does not have a distinct melting point as it does not exist as a solid compound under normal conditions. It is typically found in a solid state in the form of powders, granules, or lumps. These solid forms of Na2SiO3 have different melting points, which vary depending on their composition and preparation method.
Sodium Silicate Density g/mL
The density of Na2SiO3 solutions varies with their concentration. Na2SiO3 solutions with a concentration of 20% have a density of approximately 1.14 g/mL, while those with a concentration of 40% have a density of about 1.34 g/mL. The density of solid Na2SiO3 can range from 2.3 g/mL to 2.6 g/mL, depending on its purity and particle size.
Sodium Silicate Molecular Weight
The molecular weight of Na2SiO3, also known as its formula weight, is the sum of the atomic weights of all the atoms present in the compound. The molecular weight of Na2SiO3 is approximately 122.06 g/mol. Knowing the molecular weight of a compound is essential in determining the amount of the compound needed for a specific reaction.
Sodium Silicate Structure
Sodium silicate is an inorganic compound composed of sodium cations and polymeric silicate anions. The structure of sodium silicate can vary depending on its composition and preparation method. It is typically represented by the formula Na2O·nSiO2, where n represents the number of SiO2 units in the polymeric anion. Polymeric silicate anions have a three-dimensional network structure, where silicon atoms are tetrahedrally coordinated with oxygen atoms.
| Appearance | Colorless or white solid, liquid or powder |
| Specific Gravity | 1.4-1.6 |
| Color | Colorless |
| Odor | Odorless |
| Molar Mass | 122.06 g/mol |
| Density | 1.14-1.34 g/mL (solution); 2.3-2.6 g/mL (solid) |
| Melting Point | No distinct melting point |
| Boiling Point | 100-110 °C (solution) |
| Flash Point | Not applicable |
| Water Solubility | Soluble |
| Solubility | Soluble in water and ethanol; slightly soluble in methanol and acetone |
| Vapour Pressure | Not applicable |
| Vapour Density | Not applicable |
| pKa | ~9.8 |
| pH | 11-12 (solution) |
Sodium Silicate Safety and Hazards
Na2SiO3 can be hazardous if not handled properly. It is a caustic compound that can cause severe skin and eye irritation upon contact. Inhalation of Na2SiO3 dust or mist can cause respiratory irritation and lung damage. Na2SiO3 solutions are also highly alkaline and can cause chemical burns on the skin or mucous membranes. Proper personal protective equipment, such as gloves and eye protection, should be worn when handling Na2SiO3. In case of skin or eye contact, immediate rinsing with water is necessary. Na2SiO3 should also be stored in a cool, dry, and well-ventilated area away from incompatible materials.
| Hazard Symbols | Corrosive, Irritant |
| Safety Description | Keep out of reach of children. Avoid contact with eyes, skin, and clothing. Wear protective gloves/protective clothing/eye protection/face protection. IF ON SKIN: Wash with plenty of water. IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing. IF SWALLOWED: Rinse mouth. Do NOT induce vomiting. Call a POISON CENTER or doctor/physician if you feel unwell. |
| UN IDs | UN2922, UN1824 |
| HS Code | 2839.90.90 |
| Hazard Class | 8 |
| Packing Group | III |
| Toxicity | LD50 (oral, rat) = 1280 mg/kg; LC50 (inhalation, rat) >2.28 mg/L/4h |
Sodium Silicate Synthesis Methods
Several methods exist for synthesizing Na2SiO3.
One common method involves fusing silica with sodium carbonate at a high temperature, which produces Na2SiO3 and carbon dioxide as byproducts.
Another method involves reacting sodium hydroxide with silica in a high-pressure vessel at elevated temperatures. To achieve the desired concentration, dilute the highly concentrated Na2SiO3 solution with water.
A third method involves dissolving silica gel in sodium hydroxide solution, followed by heating and stirring the mixture to promote the reaction. This method results in a clear, colorless solution of Na2SiO3.
Microwave radiation can heat the reactants, synthesizing Na2SiO3.
These methods produce Na2SiO3 with higher purity and yields compared to traditional synthesis methods.
Additionally, some studies have explored the use of renewable resources such as rice husk ash and sugarcane bagasse ash as silica sources for Na2SiO3 synthesis, providing a more sustainable approach to production.
Sodium Silicate Uses
Na2SiO3 is a versatile compound with numerous applications in various industries. Some of the common uses of Na2SiO3 are:
- Adhesives and Binders: Used as a binder in various applications such as paperboard, corrugated boxes, and plywood.
- Detergents and Soaps: Used in laundry detergents as an alkaline buffer and an anti-redeposition agent.
- Water Treatment: Used in water treatment as a coagulant aid and as a corrosion inhibitor.
- Construction: Also used as a concrete hardener and as a soil stabilizer.
- Ceramics: Used as a binder in ceramics production.
- Textile and Paper: Used as a sizing agent in paper production and as a flame retardant in textiles.
- Automotive: Used as a sealant and a coolant additive in the automotive industry.
- Agriculture: Used as a foliar spray to improve plant growth and as a soil amendment to reduce soil compaction and increase water retention.
- Fire Protection: Used as a fire retardant in various materials such as wood, fabric, and paper.
- Personal Care: Used in some toothpaste and deodorants as a binding agent and as a viscosity control agent.
Questions:
Q: Is sodium silicate toxic?
A: Na2SiO3 can be toxic if ingested or inhaled in large amounts. It can irritate the eyes, skin, and respiratory system. However, when used in accordance with safety guidelines, such as wearing appropriate personal protective equipment, Na2SiO3 is generally safe to handle.
Q: How to cure Na2SiO3?
A: Na2SiO3 is cured by exposing it to carbon dioxide, which causes the liquid Na2SiO3 to solidify into a hard, glass-like substance. The curing time depends on the concentration of the Na2SiO3 solution and the temperature and humidity of the curing environment. Generally, it takes several days for Na2SiO3 to fully cure.
Q: Can paint over sodium silicate treated concrete?
A: Yes, it is possible to paint over Na2SiO3-treated concrete, but the surface must be properly prepared. The Na2SiO3 must be allowed to fully cure and then the surface should be cleaned and primed with a suitable primer before applying paint.
Q: Where to buy sodium silicate near me?
A: Na2SiO3 can be purchased from chemical suppliers, industrial suppliers, and online retailers. It is important to ensure that the supplier is reputable and that the Na2SiO3 is of high quality and suitable for the intended application. It is also important to follow proper handling and safety guidelines when purchasing and using Na2SiO3.