Calcium Carbide

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Related to CAC2: calcium carbide, CAO

calcium carbide

[′kal·sē·əm ′kär‚bīd]
(inorganic chemistry)
CaC2 An alkaline earth carbide obtained in the pure form as transparent crystals that decompose in water; used to make acetylene gas.

Calcium Carbide

 

CaC2 a compound of calcium and carbon; one of the most important carbides used in technology. Chemically pure calcium carbide is colorless; industrial calcium carbide varies in color from light brown to black. Calcium carbide has a density of 2.2 g/cm3, and a melting point of 2300°C. Calcium carbide interacts with water to form acetylene: CaC2+ 2H2O = C2H2 + Ca(OH)2; the process is carried out in an excess of water for withdrawal of the liberated heat (30.4 kcal/mole, that is, 127.3 kilojoules per mole). Upon heating, calcium carbide interacts with nitrogen to form calcium cyana-mide: CaC2 + N 2 = CaCN2 + C.

Calcium carbide is prepared in electric furnaces at temperatures ranging from 1900° to 1950°C according to the reaction CaO + 3C = CaC2 + CO, in which a large quantity of heat (450.5 kilojoules per mole) is absorbed. Lime and anthracite or coke serve as raw material for the process. Most of the operating carbide furnaces have an opening at the top; CO is burned down to CO2 after its discharge from the furnace. Closed furnaces with CO extraction have also been constructed. Calcium carbide has found wide application in technology, primarily in the manufacture of acetylene and calcium cynamide and in the reduction of alkali metals.

REFERENCES

Kuznetsov, L. A. Proizvodstvo karbida kaVtsiia. Moscow-Leningrad, 1950.
Strizhevskii, I. I., S. G. Guzov, and V. A. koval’skii. Atsetilenovye stantsii, 2nd ed. Moscow, 1959.
References in periodicals archive ?
CaC2 rate###Vine length Number of###Number of###Inter-nodal###Days to first###Days to###Number of###Fruit yield###Ethylene###Female
Maximum response was observed in plants treated with paint coated CaC2 at 300 mg pot-1.
Germination rate of cucumber was significantly improved at lower rates of CaC2 (10 to 30 mg CaC2 plate-1), while the highest rate of 40 mg CaC2 plate-1 suppressed germination (Table 1).
These results suggest that the effect of CaC2 on germination and morphological characteristics is concentration dependent and might follow the biphasic response model, with low rates promoting and high rates inhibiting growth (Pierik et al., 2003).
In the present study, enhanced seed germination by the application of CaC2 was significantly correlated (0.71) with increased ethylene evolution and these results were coincided as reported by Machabee and Saini (1991), and Calvo et al.
Differential response of cucumber in terms of morphological, floral and yield parameters due to the application of coated CaC2 was owing to the specific acetylene and ethylene flux from various rates and coatings of calcium carbide.
This all happened most probably due to addition of CaC2 in the soil environment.
Ethylene released from CaC2 probably stimulated adventitious roots of the plant as reported by other researchers (Rao and Fritz, 1987; Chaiwanakupt et al., 1996; Yaseen et al., 2006).
Enhanced carboxylation efficiency due to ethylene releasing compound CaC2 determines the mesophyll effects.
It is thus concluded that CaC2 affects photosynthesis through ethylene-induced increase in stomatal conductance, carboxylation efficiency and also through light interception because of increased leaf area and dry mass production which ultimately resulted in increase in water use efficiency in tomato plants.