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15-25Mm Calcium Carbide: Physical and chemical properties: ores are solid brown or black block, pure white crystals (including CaC2 higher purple). Density of 2.22 g / cubic centimeter, the melting point of 2300 ° C (with CaC2 content), water immediately intense reaction to generate acetylene, and release heat, Calcium Carbide content varies with the melting point also will change.
Impurities: Caustic soda often contain calcium arsenide (Ca3As2), calcium phosphide (Ca3P2) and other impurities, and the role of water at the same time release arsine (AsH3), phosphine (PH3) and other toxic gases, so the use of Acetylene generated by calcium carbide is toxic.
The most common crystal form of CaC2 is tetragonal, stable between 298K and 720K. Quartet CaC2 similar to the crystal structure of NaCl, but due to [: C≡C:] 2- ion oval, oriented, the crystal is tetragonal. In CaC2 crystal, the C-C distance is 120pm, which corresponds to the bond length of carbon-carbon triple bond, the distance between Ca and C is 259 and 282pm.