Search results
Results from the WOW.Com Content Network
Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula SiO 2, commonly found in nature as quartz. [ 5 ] [ 6 ] In many parts of the world, silica is the major constituent of sand .
Crystalline silica (chemically, silicon dioxide) is a very common mineral found in the earth's outside layer. Quartz is the most common type of crystalline silica. Sand, stone, cement, and mortar contain crystalline silica. It is used to make items like glass, stoneware, earthenware, blocks, and manufactured stone.
Silicon (Si) is the second most common element in the Earth's crust after oxygen. The compound silica , also known as silicon dioxide (SiO 2 ), is formed from silicon and oxygen atoms. Since oxygen and silicon make up about 75% of the Earth's crust, the compound silica is quite common.
Silica gel is an amorphous and porous form of silicon dioxide (silica), consisting of an irregular tridimensional framework of alternating silicon and oxygen atoms with nanometer-scale voids and pores. The voids may contain water or some other liquids, or may be filled by gas or vacuum.
Many gases have toxic properties, which are often assessed using the LC 50 (median lethal concentration) measure. In the United States, many of these gases have been assigned an NFPA 704 health rating of 4 (may be fatal) or 3 (may cause serious or permanent injury), and/or exposure limits (TLV, TWA/PEL, STEL, or REL) determined by the ACGIH professional association.
NFPA 704 safety squares on containers of ethyl alcohol and acetone. "NFPA 704: Standard System for the Identification of the Hazards of Materials for Emergency Response" is a standard maintained by the U.S.-based National Fire Protection Association.
Get AOL Mail for FREE! Manage your email like never before with travel, photo & document views. Personalize your inbox with themes & tabs. You've Got Mail!
Hydrated silica is a form of silicon dioxide, which has a variable amount of water in the formula. When dissolved in water, it is usually known as silicic acid . It is found in nature as opal [ 2 ] (which has been mined as a gemstone for centuries), and in the cell walls of diatoms .