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History and Production
Derived from Greek, chloros, meaning greenish yellow. It was the first of the halogens to be isolated, in 1774, by C.W. Scheele, by oxidizing hrdrochloric acid and manganese(IV) dioxide. However, he did not recognized it as a compound.
However, H. Davy insisted that it was an element and was given the name chloros in 1811 which relates to the color of the gas. The bleaching power of chlorine has
long been recognized by Scheele since 1774. To date, it is still used as such in industry. The industrial production of chlorine gas is achieved by the electrolytic process of chloride ions of natural brine.
It is also produced from electrolysis of fused sodium chloride, of which sodium metal is the byproduct. It is also used as a disinfectant, germicide and chlorination of domestic water supplies. It is also used in paper productions, textiles,
plastics and many other consumer products.
Physical Data
It is a greenish-yellow, gas, which readily dissolves in water, especially at a lower temperature. It is poisonous and has a characteristic pungent smell that irritates the mucous membrane.
The majority of chlorine is contained in the sea water reserves as chloride ions.
Interatomic distance: 198.8 pm
Melting point: -101.5°C
Boiling point: -34.04°C
Thermal conductivity/Wm-1K-1: 0.0089 (27°C)
Density/kgm-3: 1507 (b.p.), 3.214 (0°C)
Standard Thermodynamic Data (atomic gas)
Enthalpy of formation: 121.3 kJ/mol
Gibbs free energy of formation: 105.3 kJ/mol
Entropy: 165.2 J/mol K
Heat capacity: 21.8 J/mol K
Electronic data
Electronic configuration: [Ne] 3s2 3p5
Term symbol: 2P3/2
Electron affinity: 348.5751 kJ/mol Electronegativity (Pauline): 3.16
Ionization energy (first, second, third): 1251.19, 2297.70, 3821.79 kJ/mol
Chemical properties
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