Calcium carbide, is an inorganic compound, the chemical formula is CaC2, is the main component of calcium carbide, for the white crystalline powder, industrial products for gray black block, the section is purple or gray. 

Calcium carbide is an important basic chemical raw material, which is mainly used to produce acetylene gas. Also used for organic synthesis, oxyalkyne welding, etc.

Basic information

Structure and nature

Physical and chemical characteristics

Electronic: Ca 2 + [: CC:] 2-The middle "" represents three shared electronic pairs

InChI： InChI=1/C2. Ca/c1-2;/q-2;+2

Physicochemical properties: white crystalline powder. Density 2.22 g/cm3, melting point 447℃, water immediately intense reaction to produce acetylene, and release heat, reaction principle: CaC2 + 2 H2O = Ca (OH) 2 + C2H2

Crystal structure

CaC2 The most common crystal type is the tetet system, which is stable between 298K and 720K, and its structure is shown in Figure 1. The crystal structure of the tetragonal CaC2 is similar to the NaCl type, but because the 2-ions are oval and oriented, the crystal belongs to the tetragonal crystal system. In the 2-ion of the CaC2 crystal, the C-C distance is 120pm, equivalent to the bond length of the carbon-carbon triple bond, and the distance between Ca and C is 259 and 282pm.

Calcium Carbide Application

1. Acetylene produced by the reaction of calcium carbide and water can synthesize many organic compounds such as synthetic rubber, artificial resin, acetone, enone, carbon black, etc. At the same time, acetylene monooxygen flame is widely used for welding and cutting of metals.

2. When heating powdered calcium carbide and nitrogen, the reaction produces calcium cyanide, namely lime nitrogen:

CaC2 + N2 → CaCN2 + C , ΔH = -296kJ/mol

Lime nitrogen is an important raw material for the preparation of amino cyanogen. The melt produced by the reaction of heated lime nitrogen and table salt is used for gold mining and non-ferrous metal industry.

3, calcium carbide itself can be used in the iron and steel industry desulfurization agent.

4, the production of polyvinyl chloride (PVC), calcium carbide production of polyvinyl chloride using calcium carbide (calcium carbide CaC2), meet water to produce acetylene (C2H2), acetylene and hydrogen chloride (HCl) synthesis to produce vinyl chloride monomer (CH2=CHCl), and then through the polymerization reaction to produce polyvinyl chloride- - [CH2-CHCI] n-chemical reaction method.

5. In the old days, the miners put the calcium carbide into the iron tank and used the generated acetylene (C2H2) to make the calcium carbide lamp.