CHLORINE GAS: FORMULA, EFFECTS, USES AND RISKS - CHEMISTRY - 2025

The chlorine gas (dichloro, diatomic chlorine, molecular chlorine or chlorine simply) is a greenish - yellow gas with a non - combustible hot suffocating odor at room temperature and atmospheric pressure.

It is the element with the highest electron affinity and the third highest electronegativity, behind only oxygen and fluorine. It is extremely reactive and a strong oxidizing agent.

The high oxidizing potential of elemental chlorine led to the development of commercial bleaches and disinfectants, as well as a reagent for many processes in the chemical industry.

In the form of chloride ions, chlorine is necessary for all known species of life. But elemental chlorine in high concentrations is extremely dangerous and poisonous to all living organisms, which is why it was used in World War I as the first gaseous chemical warfare agent.

Chlorine gas in a bottle

It is toxic by inhalation. In the long term, inhalation of low concentrations, or short-term, inhalation of high concentrations of chlorine gas, have harmful effects on health.

Vapors are much heavier than air and tend to settle in low areas. It does not burn, but supports combustion. It is slightly soluble in water. Contact with unconfined liquids can cause evaporative cooling frostbite.

It is used to purify water, bleach wood pulp, and to make other chemicals.

Formula

Formula: Cl-Cl

CAS number: 7782-50-5

2D structure

Chlorine gas

Chlorine gas / Molecular model of spheres

characteristics

Physical and chemical properties

Chlorine gas belongs to the reactive group of strong oxidizing agents. These compounds often react vigorously with other compounds.

Chlorine gas also belongs to the reactive group of strong halogenating agents, which transfer one or more halogen atoms to the compound with which they are reacting.

Halogenating agents are generally acidic and therefore react, in some cases violently, with bases.

Many of these compounds are reactive to water and reactive to air. Halogens are highly electronegative and are strong oxidants.

Reactivity Alerts

Chlorine gas is a strong oxidizing agent. Reacts with water. Water dissolves chlorine gas, forming a mixture of hydrochloric acid and hypochlorous acids.

Inflammability

It can ignite other combustible materials (wood, paper, oil, etc.). Mixing with fuels can cause an explosion. Container may explode on contact with fire. There is a risk of explosion (and poisoning) from the accumulation of its vapors indoors, in sewers or outdoors.

Hydrogen and chlorine mixtures (5-95%) can explode by the action of almost any form of energy (heat, sunlight, sparks, etc.).

It emits highly toxic fumes when heated. When combined with water or steam it produces toxic and corrosive hydrochloric acid vapors.

Reactivity

Chlorine reacts explosively with (or supports the burning of) many common materials.

• Chlorine ignites steel at 100 ° C in the presence of soot, oxide, carbon, or other catalysts.
• Turn the dry steel wool to 50 ° C.
• Light the sulfides at room temperature.
• Ignites (in its liquid form) natural and synthetic rubber.
• Ignite trialkylborans and tungsten dioxide.
• It ignites in contact with hydrazine, hydroxylamine, and calcium nitride.
• Ignites or explodes with Arsine, Phosphine, Silane, Diborane, Stibine, Red Phosphorus, White Phosphorus, Boron, Active Carbon, Silicon, Arsenic.
• It causes ignition and a soft explosion when bubbling through cold methanol.
• It explodes or ignites if mixed excessively with ammonia and heated.
• Forms explosive nitrogen trichloride on contact with Biuret's Reagent contaminated with cyanuric acid.
• Easily forms explosive derivatives of N-chlorine with aziridine.

Chlorine (in its liquid or gaseous form) reacts with:

• Alcohols (explosion)
• Molten aluminum (explosion)
• Silanes (explosion)
• Bromine pentafluoride
• Carbon disulfide (iron catalyzed explosion)
• Chlorine-2-propyne (excess chlorine causes an explosion)
• Dibutyl Phthalate (Explosion at 118 ° C)
• Diethyl ether (lit)
• Diethyl zinc (lit)
• Glycerol (explosion at 70-80 ° C)
• Methane on yellow mercury oxide (explosion)
• Acetylene (explosion initiated by sunlight or heating)
• Ethylene on mercury, mercury (I) oxide, or silver (I) oxide (explosion caused by heat or light)
• Gasoline (exothermic reaction and then detonation)
• Naphtha-sodium hydroxide mixture (violent explosion)
• Zinc chloride (exothermic reaction)
• Wax (blast)
• Hydrogen (explosion initiated by light)
• Iron carbide
• Uranium and zirconium
• Sodium, potassium and copper hydrides
• Tin
• Aluminum powder
• Vanadium powder
• Aluminum foil
• Tinsel
• Copper foil
• Calcium powder
• Iron wire
• Manganese powder
• Potassium
• Antimony powder
• Bismuth
• Germanium
• Magnesium
• Sodium
• Zinc

Toxicity

Chlorine gas is poisonous and can be fatal if inhaled. Contact can cause skin and eye burns, as well as bronchitis or chronic lung conditions.

German WWI gas attack on the Eastern Front

Applications

About 15,000 chlorine compounds are used commercially today. Sodium chloride is by far the most common chlorine compound, and is the main source of chlorine and hydrochloric acid for the huge chlorine chemical industry.

Of all the elemental chlorine produced, approximately 63% is used in the manufacture of organic compounds, 18% in the manufacture of inorganic chlorine compounds, and the remaining 19% of chlorine produced is used for bleaches and disinfectants.

Recycling raw materials, PVC

Among the most significant organic compounds in terms of production volume are 1,2-dichloroethane and vinyl chloride (intermediate products in the production of PVC), methyl chloride, methylene chloride, chloroform, chloride of vinylidene, among others.

The main inorganic compounds include HCl, Cl2O, HOCl, NaClO3, AlCl3, SiCl4, SnCl4, PCl3, PCl5, POCl3, AsCl3, SbCl3, SbCl5, BiCl3, S2Cl2, SCl2, SOCI2, ClF3, ICl, ICl3, MoCl3, TiCl4, FeCl3, ZnCl2, and many more.

Chlorine gas is used in industrial bleaching operations, wastewater treatment, the manufacture of tablets for swimming pool chlorination or in chemical warfare.

Chlorine gas (known as bertholite), was first used as a weapon in World War I by Germany.

After its first use, both sides in the conflict used chlorine as a chemical weapon, but it was soon replaced by phosgene and mustard gas, which are more deadly.

Chlorine gas was also used during the Iraq War in Anbar province in 2007.

Clinical effects

Chlorine gas is one of the most common occupational and environmental single inhalation irritant exposures. Recent studies have reported that the mixture of bleach (bleach, made mainly based on sodium hypochlorite) with other cleaning products, is the most frequent cause (21% of cases) of single inhalation exposure reported in poison centers. from the United States.

The main toxic effects are due to local tissue damage rather than systemic absorption. Cell injury is believed to result from oxidation of functional groups on cellular components; to reactions with water in tissues to form hypochlorous acid and hydrochloric acid; and the generation of oxygen free radicals (although this idea is now controversial).

In mild to moderate poisoning there are: cough, shortness of breath, chest pain, burning sensation in the throat and in the retrosternal area, nausea or vomiting, eye and nasal irritation, asphyxia, muscle weakness, dizziness, abdominal discomfort and headache.

In severe poisoning, there is: upper airway edema, laryngospasm, severe pulmonary edema, pneumonia, persistent hypoxemia, respiratory failure, acute lung injury, and metabolic acidosis.

Chronic exposure to chlorine gas is one of the most common causes of occupational asthma. It can cause dyspnea, palpitations, chest pain, reactive upper airway dysfunction syndrome, erosion of tooth enamel, and an increased prevalence of viral syndromes. Chronic exposure to 15 ppm causes coughing, hemoptysis, chest pain, and sore throat.

Dermal exposure can cause skin erythema, pain, irritation, and burns. Severe exposure can cause cardiovascular collapse and respiratory arrest. In high concentrations, syncope and almost immediate death can occur. Chlorine (as hypochlorite) is teratogenic in experimental animals.

Safety and risks

Hazard statements of the Globally Harmonized System of classification and labeling of chemical products (GHS).

The Globally Harmonized System of Classification and Labeling of Chemicals (GHS) is an internationally agreed system, created by the United Nations designed to replace the various classification and labeling standards used in different countries by using consistent criteria at the global level (Nations Nations, 2015).

The hazard classes (and their corresponding chapter of the GHS), the classification and labeling standards, and the recommendations for chlorine gas are as follows (European Chemicals Agency, 2017; United Nations, 2015; PubChem, 2017):

GHS hazard classes

H270: May cause or intensify fire; Oxidant

H280: Contains gas under pressure; May explode if heated

H315: Causes skin irritation

H319: Causes serious eye irritation

H330: Fatal by inhalation

H331: Toxic by inhalation

H335: May cause irritation of the respiratory tract

H400: Very toxic to aquatic life

H410: Very toxic to aquatic life with long lasting effects

(PubChem, 2017)

Precautionary statement codes

P220, P244, P260, P261, P264, P271, P273, P280, P284, P302 + P352, P304 + P340, P305 + P351 + P338, P310, P311, P312, P320, P321, P332 + P313, P337 + P313, P362, P370 + P376, P391, P403, P403 + P233, P405, P410 + P403, and P501.

References

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