With the chemical formula H2CO3, carbonic acid is an inorganic substance in chemistry. It is common in water as a diluted solution, but only at temperatures about 80 °C can the pure component, a colourless gas, be produced. Contrary to popular assumption, the molecule is quite stable at room temperature in the absence of water, when it quickly breaks down into water and carbon dioxide. The interconversion of carbon dioxide and carbonic acid is influenced by both the acidity of natural waters and the breathing cycle of mammals.
Aqueous solutions of carbon dioxide frequently go by the name “carbonic acid” in biochemistry and physiology; they are crucial components of the bicarbonate buffer system, which regulates acid-base balance.
Carbonic Acid: Preparations
One carbon-oxygen double bond and two carbon-oxygen single bonds make up the structure of carbonic acid, as can be seen from the example given above. One hydrogen atom is joined to each of the oxygen atoms involved in a single bond with the carbon.
In many temperate habitats, carbonic acid, which is created when CO2 dissolves and hydrolyzes in water, is the main naturally occurring leaching agent. Because it is weak and unstable, carbonic acid quickly separates into bicarbonate ions and hydrogen ions (H+) (HCO3–)
Properties of Pure Carbonic Acid
The gaseous form of carbonic acid, H2CO3, is very stable at room temperature. It breaks down to produce carbon dioxide and water when there is water present, which speeds up the breakdown process.
Pure solid carbon dioxide is irradiated with proton beams to make pure carbonic acid, or hydrogen chloride and potassium bicarbonate react at 100 K in methanol to produce pure carbonic acid.
- A hybrid clamped cell made of a Russian alloy and copper-beryllium was used to create a high-pressure deuterated form of carbonic acid, or D2CO3, which was then studied by neutron diffraction.
- Planar molecules combine to create dimers that are connected by pairs of hydrogen bonds.
- At 1.34 Å, the three C-O bonds are almost equally spaced apart. Distances between C-O and C=O that are more common are 1.43 Å and 1.23 Å, respectively.
- Delocalized bonding in the molecule’s core and exceptionally strong hydrogen bonds, as evidenced by the O—-O separation of 2.13, are both responsible for the extraordinary C-O bond lengths.
- The 136° O-H-O enforced by the 8-membered rings with double hydrogen bonds is one cause of the short O—-O separation.
- Strong intramolecular hydrogen bonds, such as those in dicarboxylic acid, which have O—-O lengths above 2.4 Å, are known to occur.
- As ambient pressure carbonic acid does not exhibit Bragg peaks in X-ray diffraction, it must be categorised as amorphous.
Chemical Properties of Carbonic Acid
Following are the Chemical Properties of Carbonic Acid:
- Being a weak acid, H2CO3 is unstable in the natural world.
- When there is water present, it partially dissociates, releasing H+ and HCO3- (bicarbonate) ions.
- As carbonic acid is a diprotic acid, it can produce both bicarbonates and carbonates as salts.
- Bicarbonate salts are produced when a base is added in modest amounts to H2CO3, whereas carbonate salts are produced when a base is added in large amounts.
Physical Properties of Carbonic Acid
Following are the Physical Properties of Carbonic Acid:
- Carbonic acid has a molar mass of 62.024 grammes per mole.
- It has a density of 1.668 grammes per cubic centimetre in its normal state.
- The pKa value of the substance H2CO3 is 6.35.
- The bicarbonate is the conjugate base that corresponds to carbonic acid.
- The most common form of this chemical is a solution. Nonetheless, it has been stated that NASA scientists have generated solid H2CO3 samples.
Uses of Carbonic Acid
Following are the uses of Carbonic Acid:
- Carbonic acid is used in the production of sparkling wine, carbonated water, and other aerated beverages.
- The precipitation of several ammonium compounds, including ammonium persulfate, uses H2CO3.
- It facilitates the removal of carbon dioxide from the body.
- H2CO3 protonates a number of bases containing nitrogen in blood serum.
- Treatment for ringworm and other dermatitides involves applying carbonic acid to the affected region.
- Contact lens cleaning solutions that contain this substance work quite well.
- When necessary, it can be taken orally to cause vomiting (such as in drug overdose cases).
Carbonic Acid: Importance
Importance of Carbonic Acid in Blood: It is well known that the bicarbonate ion functions as an intermediary in the process of respiratory gas exchange, which transports carbon dioxide from the human body. Carbon dioxide’s hydration processes go very slowly, especially when a sufficient catalyst is not present. Nevertheless, the carbonic anhydrases enzyme family is found in red blood cells, which speeds up the reaction.
The enzymes known as carbonic anhydrases catalyse the transformation of water and carbon dioxide into the dissociated ions of carbonic acid. This results in the formation of bicarbonate anions, which dissolve in the blood plasma. In the lungs, the catalysed reaction is reversed, creating CO2, which is subsequently breathed.
Importance of Carbonic Acid in Ocean: The pH of the ocean’s water is thought to have changed by about -0.1 due to the oceans’ absorption of the extra carbon dioxide in the atmosphere, which is mostly the result of human activity. Ocean water and the absorbed carbon dioxide combine to make H2CO3. Ocean acidification is the term generally used to describe this process.
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