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Home >> Chemistry Dictionary >> Cadmium Chemistry Calcination
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Ca
Calcium.
Cacodyl derivatives.
Organoarsenic compounds containing the AsMe2 grouping .
Cadinene
C15H24 A. sesquierpene of very wide distribution.
Cadmium, Cd.
At. no. 48, at. wt. 112.41, m.p. 20.9°C, b.p. 765°C, d 8.64. Cadmium occurs in Zn and also Pb and Cu ores but also as greenokite, Cds. Cd is more volatile than Zn and is collected in the dust in flues of furnaces for producing zinc. CdO is reduced with C or Cd2+ is reduced in zinc solution with dust. Cd is a white lustrous metal with a deformed hcp structure with 6 near (in plane) and 6 far neighbours.
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. The metal reacts with oxygen on heating and with acids. Cd is used extensively for electroplating (35%) and in fusible alloys), batteries, atomic reactors; cadmium compounds are used pigments, plasticizers and as phosphorus in colour TV tubes. Cadmium telluride has many electronic applications. Cadmium compounds are very toxic.
Cadmium chemistry.
Cadmium is an electropositive element with a filled d shell, electronic configuration 4d105s2. The only stable oxidation state is +2 frequency in a mainly ionic state.
E° for Cd2+--> Cd in acid solution — 0.402 volts
An unstable lower oxidation state is found in Cd—CdCl2 and Cd—CdCl2 —AlCl3 melts and may contain cd—Cd bonds. The common co-ordination number for Cd2+ is 6 (octahedral) although 4 and 5 co-ordination are known.
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Cadmium oxide, Cdo ; Cadmium hydroxide Cd(OH)2.
The hydroxide is precipitated from aqueous solution by OH-, it does not dissolve in excess OH-. Ignition of Cd(OH)2 or CdCo3 gives CdO which varies in colour from red-brown to black because of lattice defects.
Cadmium oxy-acid salts
A colourless salts prepared by solution of the oxide or carbonate m the appropriate acid.
Cadmium sulphide.
A water-insoluble compound, Cds; r.d. 4.82. It occurs naturally as the mineral greenokite and is used as a pigment and in semiconductors and fluorescent materials.
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Cadmium Yellow.
Natural cadmium sulphide. Used as a pigment.
Caesium.
A soft silvery white metal belongs to IA group of the periodic table. It is highly reactive. Its alloys are used in the manufacture to radiotubes and photoelectric cells. An alloy of caesium and silver used in the electric eye used in television.
Symbol. Cs ; a.n. 55 ; m.p. 28.5° C; b.p. 690°C ; r.d. 1.87.
Caesium chloride. CsCl
A typical alkali halide formed from Cs2CO3 and HCl. The structure is that adopted by many compounds AX with a large radius ratio of A : X. Each ion has a co-ordination number eight. A-dopted by CsCl, Csl, AgLi, HgTl, etc.
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Caffeine, 1,3, 7- trimethylxanthine, theine,
C8H10 N4O2. An alkaloid occuring in tea, coffee and guarana, from which it may be prepared by extraction. It also manufactured by the Methylation of theobromine and by the condensation of cyanoacetic acid with urea. Crystallizes with H2O or anhydrous from organic solvents. M.p. (anhydrous). 235°C. sublimes at 176°C Odourless, and with a very bitter taste. Caffeine acts as a stimulant and diuretic, and is a constituent of cola drinks, tea and coffee.
Calamine,
ZnCO3 (British), ZnSiO4, H2O (U.S). Medical calamine is a basic zinc carbonate coloured with Fe2O3. Formerly obtained from the carbonate now obtained by precipitation. Used either in location or as a powder for sunburn, sore skin and dermatitis.
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Calcination
The term used for the formation of a calcium carbonate deposit from hard water.
Calcine.
(1) To drive off volatile components from a solid by heating to a high temperature. (2) To form a metal oxide by heating the metal at a high temperature in air or oxygen.
Calcium,
Ca. At. no. 20, at. wt. 40.08, m.p. 839°C, b.p. 1484°C, dl. 54 Calcium compounds are widely distributed in nature occurring as CaCo3 (marble, limestone, chalk, calcite, aragonite, dolomite), CaSO4 (gypsum), Ca3(PO4)2 halides and silicates (various feldspars, anorthite). The metal is obtained by electrolysis of the fused chloride or by CaCO3, plus Al at high temperature and pressure. It is a soft silvery white ccp at room temperature hcp above 450°C. It tarnishes rapidly in air, reacts violently with water combines with oxygen and the halogens. Ca is used as a reducing agent in the preparation of metals such as Th, V, Zr, as a deoxidizer and as an alloying agent. Calcium oxide is the most important base of the chemical industry. Ca2+ ions are important in biological systems Calcium is an essential element for living organisms, being required for normal growth and development.
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