Chlorine : Chlorine, Chemical Properties

Chlorine is a very active element; it readily combines directly with hydrogen, and with most metals and non-metallic elements except nitrogen, oxygen, and carbon. Reaction often occurs when the elements are brought together at the ordinary temperature, frequently with the production of flame, or incandescence.

The reaction with metals does not always take place if the chlorine is dry, although pure dry mercury completely absorbs pure dry chlorine. T. Andrews (1842) found that dry copper and zinc do not react with dry chlorine. Reaction between dry materials occurs in the cases of arsenic, antimony, mercury and phosphorus. Bromine behaves similarly. Sodium may be melted in dry chlorine without reaction taking place (Wanklyn, 1883). In the following experiments, therefore, undried chlorine is to be used.

Expt. 6. - Sprinkle a little finely powdered arsenic and antimony into jars of chlorine. The substances burn, producing poisonous fumes of the chlorides AsCl₃, and SbCl₅.

Expt. 7. - A piece of phosphorus in a deflagrating spoon ignites spontaneously in chlorine, burning with a pale flame, and producing fumes of the chlorides PCl₃ and PCl₅.

Expt. 8. - Pass chlorine over a piece of sodium heated in a hard glass bulb tube.

Fig: Combustion of sodium in chlorine

When strongly heated, the metal burns with an exceedingly brilliant yellow flame, producing sodium chloride, NaCl.

Expt. 9. - A jet of hydrogen burning in air continues to burn, with an enlarged greenish flame, when introduced into a jar of chlorine,

Fig: Combustion of hydrogen in chlorine

producing hydrogen chloride:

H₂ + Cl₂ = 2HCl. A jet of chlorine burns when introduced into an inverted jar of hydrogen which is burning at the mouth.

Expt. 10. - A piece of dry red flannel and some dry litmus paper suspended in a jar of chlorine, into which some concentrated sulphuric acid has been poured, are not bleached. In moist chlorine bleaching occurs.

Expt. 11. - A burning taper plunged into a jar of chlorine burns with a small dull-red flame, clouds of black carbon and white fumes of hydrochloric acid being evolved. Paraffin wax is a mixture of hydrocarbons, the chlorine removes the hydrogen, forming HCl, and sets free the carbon, with which it does not combine directly.

Expt. 12. - A mixture of 2 vols. of chlorine and 1 vol. of ethylene C₂H₄, when ignited, burns with a red flame, emitting dense black clouds of carbon: C₂H₄ + 2Cl₂ = 2C + 4HCl.

Expt. 13. - A mixture of 2 vols. of chlorine and 1 vol. of methane CH₄, prepared out of direct sunlight, ignited with a taper, burns with a feeble whistling noise, giving fumes of hydrochloric acid and a cloud of carbon: CH₄ + 2Cl₂ = C + 4HCl.

Expt. 14. - -A little turpentine, C₁₀H₁₆, boiled in a test-tube and poured on filter-paper, catches fire when plunged into chlorine, giving a black cloud of carbon and fumes of hydrochloric acid.

Chlorine combines directly with the gases sulphur dioxide, SO₂, carbon monoxide, CO, and ethylene, C₂H₄, producing sulphuryl chloride, SO₂Cl₂, carbonyl chloride (phosgene), COCl₂, and ethylene dichloride, C₂H₄Cl₂, respectively. The carbon monoxide and sulphur dioxide react with chlorine in presence of animal charcoal; ethylene combines with chlorine on exposure to light, an oily liquid being formed.

Protein crystallography
Chemistry guide
Chlorine
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