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Calcium carbide

Calcium carbide
Calcium Carbide
Karbid vápenatý.JPG
Names
IUPAC name
Calcium carbide
Identifiers
3D model (Jmol)
ChemSpider
ECHA InfoCard 100.000.772
PubChem CID
Properties
CaC2
Molar mass 64.099 g/mol
Appearance White powder to grey/black crystals
Density 2.22 g/cm3
Melting point 2,160 °C (3,920 °F; 2,430 K)
Boiling point 2,300 °C (4,170 °F; 2,570 K)
decomposes
Structure
Tetragonal
D174h, I4/mmm, tI6
6
Thermochemistry
70 J·mol−1·K−1
−63 kJ·mol−1
Hazards
NFPA 704
Flammability code 4: Will rapidly or completely vaporize at normal atmospheric pressure and temperature, or is readily dispersed in air and will burn readily. Flash point below 23 °C (73 °F). E.g., propane Health code 1: Exposure would cause irritation but only minor residual injury. E.g., turpentine Reactivity code 2: Undergoes violent chemical change at elevated temperatures and pressures, reacts violently with water, or may form explosive mixtures with water. E.g., phosphorus Special hazard W: Reacts with water in an unusual or dangerous manner. E.g., cesium, sodiumNFPA 704 four-colored diamond
Flash point 305 °C (581 °F; 578 K) (acetylene)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
YesY  (what is YesYN ?)
Infobox references

Calcium carbide is a chemical compound with the chemical formula of CaC2. Its main use industrially is in the production of acetylene and calcium cyanamide.

The pure material is colorless, however pieces of technical-grade calcium carbide are grey or brown and consist of about 80–85% of CaC2 (the rest is CaO (calcium oxide), Ca3P2 (calcium phosphide), CaS (calcium sulfide), Ca3N2 (calcium nitride), SiC (silicon carbide), etc.). In the presence of trace moisture, technical-grade calcium carbide emits an unpleasant odor reminiscent of garlic.

Applications of calcium carbide include manufacture of acetylene gas, and for generation of acetylene in carbide lamps; manufacture of chemicals for fertilizer; and in steelmaking.

Calcium carbide is produced industrially in an electric arc furnace from a mixture of lime and coke at approximately 2200 °C. This method has not changed since its invention in 1892:

The high temperature required for this reaction is not practically achievable by traditional combustion, so the reaction is performed in an electric arc furnace with graphite electrodes. The carbide product produced generally contains around 80% calcium carbide by weight. The carbide is crushed to produce small lumps that can range from a few mm up to 50 mm. The impurities are concentrated in the finer fractions. The CaC2 content of the product is assayed by measuring the amount of acetylene produced on hydrolysis. As an example, the British and German standards for the content of the coarser fractions are 295 L/kg and 300 L/kg respectively (at 101 kPa pressure and 20 °C temperature). Impurities present in the carbide include phosphide, which produces phosphine when hydrolysed.


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