Sodium silicate

Sodium silicate
General
Systematic name	Sodium metasilicate
Other names	Liquid Glass Water Glass
Molecular formula	Na2O3Si
Molar mass	Molar mass::122.06 g/mol
Appearance	white crystals or clear liquid
CAS number	CAS number::6834-92-0
Properties
Density and phase	2.4 g/mol, solid
Solubility in water	Highly miscible
Melting point	Melting point::1088°C
Boiling point	Boiling point::102°C
Structure
Crystal structure	monoclinic
Hazards
MSDS	Sodium Silicate
Main hazards	Eye/Skin irritant, harmful if swallowed.
NFPA 704	0 2 0
Flash point	Not Flammable
R/S statement	R: 34, 37 S: 1/2, 13, 24/25, 36/37/39, 45
RTECS number	VV9275000
Related compounds
Related anions	sodium carbonate sodium germanate sodium stannate sodium plumbate
Related cations	Potassium silicate
Related compounds	sodium ortho silicate sodium pyro silicate sodium aluminosilicate
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Disclaimer and references

Sodium silicate or as it is most commonly known as, water glass, is a very unique compound that has many uses in the modern world, including commercial and scientific applications. Commonly bought commercially in either an aqueous or solid from, it has many uses, including adhesives, various cements, pulp, paper, detergents, soaps, in the automotive industry, and even kitty litter. Sodium silicate greatly influences how our modern technology works, but it gets less credit than it deserves; usually being the "little packet at the bottom of the bag." It is commonly known that it keeps whatever it is around dry, but there is actually a surprising amount of interesting properties behind this ability.

Properties

Sodium silicate is mostly produced in aqueous solutions, although it is possible to find it in a solid state. Although the physical appearance varies according to what the company is producing it for, the most common form is a white powdery crystal dissolved in pure water. It gets its nickname of "water glass" because when mixed, this powder and water solution becomes glossy, looking almost like glass. In terms of solubility, it is very soluble in water. It has the property that makes it maintain stability in a neutral or alkaline solution. Another property of sodium silicate is that when a solution that it is in becomes more acidic, the the silicate ions become more reactive with any available hydrogen ions. When this occurs, silicic acid is produced. This silicic acid is commonly used in the formation of silica gels. When hydrated, sodium silicate's melting point is greatly reduced, i.e. when in the automotive industry it is used in the form of pentahydrate sodium silicate, which has a melting point of about 72 degrees Celsius.

Occurrences

Sodium silicate is not naturally found in nature. However, it can be synthesized by adding silica sand and sodium carbonate, or soda ash, and putting it in a furnace at about 2,400 degrees Fahrenheit. The end result is a molten glass, which should then be cooled and added to a dissolver vessel, which basically adds steam and hot water. The sodium carbonate, or soda ash, is added to allow the solution to have a higher solubility. When it is made, how much soda ash is added depends on what the company that is selling it needs in its final product. These final products can also be altered in other ways, such as the "alkali change," in which the ratio of SiO₂ to Na₂O is reduced by adding an alkali or colloidal silicate, dilution, in which water is added to the silicate solution, or even by adding other ingredients, i.e. iron, aluminum, boron, etc.

Uses

Sodium silicate being used as a sealant.

Sodium Silicate is a compound that can be used in many ways, but its main uses are:

Adhesives and Cements: When in liquid form, sodium silicate is used to seal fiber drums, paper tubes, and other materials. It is the most suitable for this job because of its ability to set up quickly and to firmly hold things together. It is used as a common adhesive because of its property to lose a small amount of water and change from a liquid to a semi solid form. It makes a good cement because it is easily applied, it has a very low cost, and it is a strong binder for many different surfaces. It is used in cement for acid proof construction, refractory uses, and binding thermal insulating materials.

Pulp and Paper: Sodium Silicate is useful in de-inking, sizing, coating, and bleaching of recycled paper products. It brightens both hard and soft woods, which are used to make napkins, towels, magazine paper, and sometimes higher quality printing papers. In terms of recycled paper, it helps de-inking and repulping. Silicates also stabilize the peroxide bleaching steps, which gives recycled paper a whiter pulp.

Detergents and Soaps: Both the liquid and the solid grainy form of sodium silicate are commonly used in various cleaning operations. Metal cleaning, textile processing, washing dishes, dairy equipment, bottles, floors, and locomotives all are cleaned using some form of sodium silicate. More specifically in the textile industry, it is used in coordination with bleaches, soaps, wetting agents, and synthetic detergents in various cleaning operations.

Cat Litter: One used for sodium silicate is to be turned in to silica gel. The first people to think to used this gel in cat litter were Dan and Russell Schlueter in 1997. They were at a pet trade show where they observed someone demonstrating a bowl of pellets that absorbed massive amounts of water. Silica gel is a desiccant, meaning it is a hygroscopic substance that can be used as a drying agent. Needless to say, they ended up making a deal with the biggest silica gel maker in China. They later even ended up buying most of the company.

Applications in Modern Science

Silica gel is a common scientific application.

Sodium silicate is a very unique compound that does indeed have many applications in modern science. The first is silica gels. These gels are made of silica in its granular form. It is extremely porous, which means that water can pass through it easily. Despite it being called a gel, it is technically a solid. This silica gel was first developed during World War I as a desiccant in gas masks. Later, in World War II, it was being used to stop penicillin from spoiling, and also to stop moisture from damaging the soldier's equipment. In chemistry, it is used in the process of chromatography, as well as thin layer chromatography, where it is applied to layers of glass or aluminum. Today, in medicine it is used to protect medicines from going bad, as well as to keep bacteria away from syringes, breathing aids, and drug testing kits. In the electron science, it was found to keep moisture off of computer parts, which could damage any electronics.