Silica SiO2 Specification: 1-3mm/2-4mm

SiO2 is also known as silica. It is widely distributed in nature, such as quartz and quartz sand. White or colorless, the higher the iron content is light yellow. Density 2.2 ~ 2.66. Melting point 1670 ° C (scale quartz); 1710 ° C (cristobalite). The boiling point is 2230 ° C and the relative dielectric constant is 3.9. It is insoluble in water and slightly soluble in acid. It acts in the form of particles and acts on molten alkali. Used in glass, water glass, pottery, enamel, refractory, ferrosilicon, molding sand, elemental silicon, etc.

Silica SiO2 use:

Silicon standard solution. Water glass, a material for the preparation of silicon compounds. A mask film and a protective layer for diffusion of impurities in transistors and integrated circuits are used to form a silicon dioxide film as an integrated circuit device. Glass industry.

The bond energy of Si—O bond in SiO 2 is very high, and the melting point and boiling point are high (melting point 1723 ° C, boiling point 2230 ° C).

SiO2 + 4HF = SiF4↑ + 2H2O

Acid oxygenity:

Silica and basic oxides

SiO2 + CaO = (high temperature) CaSiO3

Silica can be dissolved in concentrated hot alkaline solution:

SiO2 + 2NaOH = Na2SiO3 + H2O

(The reason why the reagent bottle of the alkali can not use the glass stopper and the rubber stopper)

At high temperatures, silica can be reduced by carbon, magnesium, and aluminum:

SiO2+2C=(high temperature)Si+2CO

Silica SiO2 physical properties:

Silica is also known as silica, and its chemical formula is SiO2. There are two kinds of crystalline silica and amorphous silica in nature. Crystalline silica is classified into quartz, tridymite and cristobalite due to its different crystal structure. Pure quartz is a colorless crystal, and large, transparent prismatic quartz is called crystal. If the crystal containing trace impurities has different colors, there are amethyst, sap, crystal and so on. Ordinary sand is a fine quartz crystal with yellow sand (more iron impurities) and white sand (less impurities, purer). In the silica crystal, the four valence electrons of the silicon atom form four covalent bonds with four oxygen atoms, the silicon atoms are located at the center of the regular tetrahedron, and the four oxygen atoms are located at the four vertex angles of the regular tetrahedron, SiO2 It is the simplest form of composition, and it is only the ratio of the number of atoms of silicon and oxygen in the silica crystal. Silica is an atomic crystal.

The diatomaceous earth existing in nature is amorphous silica, which is the remains of lower aquatic plant diatoms. It is a white solid or powdery, porous, light and soft solid with strong adsorption.