CARBON DIOXIDE: CHARACTERISTICS, USES AND DANGERS - CHEMISTRY - 2025

The carbon dioxide is a colorless, odorless temperatures and atmospheric pressures gas. It is a molecule made up of a carbon atom (C) and two oxygen atoms (O). Forms carbonic acid (a mild acid) when dissolved in water. It is relatively non-toxic and fireproof.

It is heavier than air, so it can cause suffocation when moved. Under prolonged exposure to heat or fire, its container may rupture violently and expel projectiles.

It is used to freeze food, to control chemical reactions and as a fire extinguishing agent.

• Formula: CO2
• CAS number: 124-38-9
• UN: 1013

2D structure

characteristics

Physical and chemical properties

Molecular weight:	44.009 g / mol
Sublimation point:	-79 ° C
Solubility in water, ml / 100 ml at 20 ° C:	88
Vapor pressure, kPa at 20 ° C:	5720
Relative vapor density (air = 1):	1.5
Octanol / water partition coefficient as log Pow:	0.83

Carbon dioxide belongs to the group of chemically non-reactive substances (along with argon, helium, krypton, neon, nitrogen, sulfur hexafluoride, and xenon, for example).

Inflammability

Carbon dioxide, like the group of chemically non-reactive substances, is not flammable (although they can become so at very high temperatures).

Reactivity

Chemically non-reactive substances are considered non-reactive under typical environmental conditions (although they can react under relatively extreme circumstances or under catalysis). They are resistant to oxidation and reduction (except in extreme conditions).

When suspended in carbon dioxide (especially in the presence of strong oxidants such as peroxides) powders of magnesium, lithium, potassium, sodium, zirconium, titanium, some magnesium and aluminum alloys, and heated aluminum, chromium and magnesium are flammable and explosive.

The presence of carbon dioxide can cause a violent decomposition in solutions of aluminum hydride in ether, when the residue is heated.

The hazards arising from the use of carbon dioxide in fire prevention and extinguishing systems for confined volumes of air and flammable vapors are currently being evaluated.

The risk associated with its use is centered on the fact that large electrostatic discharges can be created that initiate the explosion.

Contact of liquid or solid carbon dioxide with very cold water can lead to vigorous or violent boiling of the product and extremely rapid vaporization due to the large temperature differences involved.

If the water is hot, there is a possibility that a liquid explosion could occur due to "overheating." Pressures can reach dangerous levels if liquid gas comes into contact with water in a closed container. Weak carbonic acid is formed in a non-hazardous reaction with water.

Toxicity

Chemically non-reactive substances are considered non-toxic (although gaseous substances in this group can act as asphyxiants).

Prolonged inhalation of concentrations equal to or less than 5% of carbon dioxide causes increased respiratory rate, headache, and subtle physiological changes.

However, exposure to higher concentrations can cause loss of consciousness and death.

Liquid or cold gas can cause frostbite injuries to the skin or eyes similar to a burn. Solid can cause cold contact burns.

Applications

Uses of carbon dioxide gas. A large proportion (approximately 50%) of all recovered carbon dioxide is used at the point of production to make other commercially important chemicals, primarily urea and methanol.

Another important use of carbon dioxide near the source of the gas is in the enhanced recovery of oil.

The remainder of the carbon dioxide generated around the world is converted to its liquid or solid form for use elsewhere, or is vented to the atmosphere, as the transport of carbon dioxide gas is not economically viable.

Uses of solid carbon dioxide

Dry ice was originally the more important of the two non-gaseous forms of carbon dioxide.

Its use first became popular in the United States in the mid-1920s as a refrigerant for food preservation, and in the 1930s it became a major factor in the growth of the ice cream industry.

After World War II, changes in compressor design and the availability of special low-temperature steels made it possible to liquefy carbon dioxide on a large scale. Therefore, liquid carbon dioxide began to replace dry ice in many applications.

Uses of liquid carbon dioxide

The uses for liquid carbon dioxide are many. In some its chemical composition matters and in others it does not.

Among these we have: use as an inert medium, to promote plant growth, as a heat transfer medium in nuclear power plants, as a refrigerant, uses based on the solubility of carbon dioxide, chemical uses and other uses.

Use as an inert medium

Carbon dioxide is used in place of an air atmosphere when the presence of air would cause undesirable effects.

In the handling and transport of food products, oxidation of the same (which leads to a loss of taste, or the growth of bacteria) can be avoided by using carbon dioxide.

Use to promote plant growth

This technique is applied by fruit and vegetable growers, who introduce the gas into their greenhouses to give plants levels of carbon dioxide higher than those normally present in the air. Plants respond with an increase in their carbon dioxide assimilation rate, and with an increase in production of around 15%.

Use as a heat transfer medium in nuclear power plants

Carbon dioxide is used in certain nuclear reactors as an intermediate heat transfer medium. It transfers the heat from fission processes to steam or boiling water in heat exchangers.

Use as a refrigerant

Liquid carbon dioxide is widely used for freezing food and also for its later storage and transportation.

Uses based on the solubility of carbon dioxide

Carbon dioxide has a moderate solubility in water, and this property is used in the production of effervescent alcoholic and non-alcoholic beverages. This was the first major application of carbon dioxide. The use of carbon dioxide in the aerosol industry is constantly increasing.

Chemical uses

In the production of foundry molds and cores, the chemical reaction between carbon dioxide and silica is used, which serves to join the grains of sand.

Sodium salicylate, one of the intermediates in the manufacture of aspirin, is made by reacting carbon dioxide with sodium phenolate.

Carbonation of softened waters is carried out using carbon dioxide to remove the precipitation of insoluble lime compounds.

Carbon dioxide is also used in the production of basic lead carbonate, sodium, potassium and ammonium carbonates, and hydrogen carbonates.

It is used as a neutralizing agent in mercerization operations in the textile industry because it is more convenient to use than sulfuric acid.

Other uses

Liquid carbon dioxide is used in a coal extraction process, it can be used to isolate certain aromas and fragrances, anesthesia of animals before slaughter, cryo-branding of animals, generation of fog for theatrical productions, examples of such uses are freezing of benign tumors and warts, lasers, production of lubricating oil additives, tobacco processing, and pre-burial sanitation.

Clinical effects

Exposure to asphyxiants occurs primarily in industrial settings, occasionally in the context of natural or industrial disasters.

Simple asphyxiants include, but are not limited to, carbon dioxide (CO2), helium (He), and gaseous hydrocarbons (methane (CH4), ethane (C2H6), propane (C3H8), and butane (C4H10)).

They act by displacing oxygen from the atmosphere, leading to a decrease in the partial pressure of alveolar oxygen and, consequently, hypoxemia.

Hypoxemia produces a picture of initial euphoria, which can compromise the patient's ability to escape the toxic environment.

CNS dysfunction and anaerobic metabolism indicate severe toxicity.

Mild to moderate intoxication

Oxygen saturation can be below 90%, even in asymptomatic or mildly symptomatic patients. It occurs with decreased night vision, headache, nausea, compensatory increase in respiration and pulse.

Severe poisoning

The oxygen saturation can be 80% or less. There is decreased alertness, drowsiness, dizziness, fatigue, euphoria, memory loss, decreased visual acuity, cyanosis, loss of consciousness, dysrhythmias, myocardial ischemia, pulmonary edema, seizures, and death.

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 GHS chapter), the classification and labeling standards, and the recommendations for carbon dioxide are as follows (European Chemicals Agency, 2017; United Nations, 2015; PubChem, 2017):

(United Nations, 2015, p.345).

(United Nations, 2015, p.346).

References

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