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Carbon Dioxide Definition
Carbon Dioxide is an inorganic molecule with the chemical formula CO2, which is made up of two oxygen atoms connected by a covalent bond to a single carbon atom and is required for many biochemical and biological activities. Carbon dioxide, carbon (iv) oxidem carbonic anhydride, carbonic oxide, carbonic-acid gas, dry ice are all synonyms for carbon dioxide (solid phase).
What is Carbon Dioxide?
Carbon dioxide (CO2) was the first gas to be identified as distinct from regular air. When Jan Baptist van Helmont, a Flemish scientist, burnt charcoal in a confined vessel around 1630, he discovered a vapour different from the air. The vapour was dubbed “wood gas” by him and them (spiritus sylvestris).
He assumed it was a single material or an ingredient. When a Scottish physician, Joseph Black, was heating calcium carbonate in 1756, he detected this gas (CaCO3). It was dubbed “fixed air” by him.
It was also recognised by exhaled breath, which he characterised as heavier than the air and slightly acidic. This material, according to English chemist John Dalton, is made up of one carbon atom and two oxygen atoms. It is now known as “carbon dioxide.”
A carbon atom and two oxygen atoms make up carbon dioxide, a chemical molecule. A double covalent connection connects each of the oxygen atoms to the centre carbon atom. The length of the C-O bond is 116.3 pm. The chemical has a linear and centrosymmetric structure. CO2 is its chemical formula. Carbon dioxide is an incombustible gas that is colourless and odourless.
Carbon dioxide may be found in a variety of forms, including gas, liquid, and solid. Dry ice is carbon dioxide that has been frozen. At normal atmospheric pressure, it reaches a temperature of -78.5°C.
An inorganic chemical is one that does not include carbon atoms and is not generated by a living organism (Vitalism). Carbon dioxide, however, is an exception to this basic norm. Carbon dioxide is a gas that contains a carbon atom and may be generated by living organisms through respiration. It, on the other hand, lacks the C-C and C-H covalent bonds seen in organic molecules.
This molecule is nonpolar due to the linearity and centrosymmetry of carbon dioxide. The distribution of valence electrons is not uneven. As they draw the electron density from the carbon at 180 degrees, the two oxygen atoms have equal force or electronegativity.
As a result, no net electron moving happens in any direction, and no net charge builds up on any of the atoms. Carbon dioxide, on the other hand, is only soluble in water while pressure is maintained. It produces carbonic acid, a weak acid, when it interacts with water.
The following is the chemical reaction:
CO2 + H2O ⇌ H2CO3
Carbon dioxide may thus be found in oceans, seas, rivers, lakes, groundwater, glaciers, and ice caps in addition to the atmosphere. When the pressure goes below 5.1 atm, the liquid carbon dioxide reverts to a gaseous state.
The molar mass of carbon dioxide is 44.01 gmol-1. It has a melting point of -56.6 degrees Celsius. It has a density of 1.98 kg/m3 at normal temperatures and pressure. At 21 °C, it has a specific gravity of 1.53. It’s a noncombustible gas.
Carbon Dioxide in Carbon Cycle
Carbon is the universe’s fourth most prevalent element. The carbon cycle is a biogeochemical cycle that depicts the exchange of carbon on Earth. Carbon is cycled through the lithosphere, hydrosphere, and atmosphere of the Earth.
Carbon is mostly found in the atmosphere as carbon dioxide and methane. The greenhouse effect is mostly caused by these two reasons. Although carbon dioxide is second only to methane in terms of greenhouse gas production per volume, it is longer-lived and occurs in considerably higher concentrations.
As a result, carbon dioxide, rather than methane, is regarded as a significant greenhouse gas. The amount of carbon dioxide in the atmosphere has increased throughout time. Human activities are one of the primary causes that have contributed to this increase.
The content of carbon dioxide in the atmosphere had risen to over 43% at the start of the Age of Industrialization. The burning of fossil fuels is primarily to blame for this. Deforestation also contributed.
Carbon dioxide is mostly absorbed by trees and other photosynthetic organisms. Carbon dioxide would not be consumed at all if they were not there, and would so build in the atmosphere. Biomass burning and cement manufacturing are two more human activities. Carbon dioxide emissions from human activities are a major source of carbon dioxide on the planet. They emit around 29 billion tonnes of CO2 each year.
Biological activities, including respiration and organic matter breakdown, are other natural, biogenic sources of carbon dioxide. During cell respiration, oxygen is taken in and processed to generate chemical energy (e.g. ATP).
Carbon dioxide is one of the metabolic byproducts of cell respiration. Carbon dioxide is gathered from cells and tissues in humans and other animals, and it is eventually exhaled outside the body. The process of breakdown or decay of organic materials can also produce carbon dioxide. Other natural sources of carbon dioxide include volcanoes, hot springs, and geysers, in addition to biogenic sources.
Volcanoes, in particular, emit between 0.2 and 0.3 billion tonnes of CO2 per year. Carbon dioxide is also produced by carbonate rocks dissolved in water and acids. At pressures of more than 5.1 atm, carbon dioxide dissolves in many bodies of water. When pressures fall, it returns to the atmosphere as a gas.
Biological Importance of Carbon Dioxide
Carbon dioxide is one of the most important inorganic chemicals for life. Carbon dioxide is a chemical molecule that accumulates in the tissues of animals and is exhaled out of the body. As a result, it is a metabolic consequence of carbohydrate metabolism, particularly cellular respiration, in which carbohydrate or lipid is digested to produce metabolic energy like ATP.
Photoautotrophic organisms like plants and cyanobacteria use carbon dioxide as a key reactant in photosynthesis to generate carbohydrates. The photosynthesis chemical process is as follows:
n CO2 + n H2O → (CH2O)n + n O2
Photosynthesis is the most common way for carbon dioxide to be removed from the atmosphere.
Carbon Dioxide Uses
In the food sector, carbon dioxide is primarily utilised in the production of carbonated beverages. It’s also utilised as a refrigerant and a coolant. Because it is denser than air and nonflammable, it is also an efficient fire extinguisher.
Carbon Dioxide Citations
- Importance of carbon dioxide in the critical patient: Implications at the cellular and clinical levels. Med Intensiva (Engl Ed) . 2019 May;43(4):234-242.
- Review of post-combustion carbon dioxide capture technologies using activated carbon. J Environ Sci (China) . 2019 Sep;83:46-63.
- Green carbon dioxide. ChemSusChem . 2011 Sep 19;4(9):1179-81.