What is Carbonic Acid?
Carbonic acid is a carbon-containing compound which has the chemical formula H2CO3. Solutions of carbon dioxide in water contain small amounts of this compound. Its chemical formula can also be written as OC(OH)2 since there exists one carbon-oxygen double bond in this compound.
Carbonic acid is often described as a respiratory acid since it is the only acid that is exhaled in the gaseous state by the human lungs. It is a weak acid and it forms carbonate and bicarbonate salts.
H2CO3 can dissolve limestone, which leads to the formation of calcium bicarbonate (Ca(HCO3)2. This is the reason for many features of limestone, such as stalagmites and stalactites.
Uses of Carbonic Acid
#1. In blood.
Carbonic acid plays an important role in respiratory gas exchange to transport carbon dioxide out of the body. It also plays an important role to protonate various nitrogen bases in blood serum.
#2. In soda water.
Water is made fizzy by adding carbon dioxide under pressure, which results in the formation of a weak acid- carbonic acid.
#3. To treat dermatitides.
Dermatitides such as ringworm can be treated by the topical application of carbonic acid.
#4. To induce vomiting.
In case of drug overdose or poisoning, carbonic acid is given orally to induce vomiting.
#5. In contact lenses.
Carbonic acid solutions are very effective in cleaning contact lenses.\
Importance of Carbonic Acid in Blood
The bicarbonate ion is known to be an intermediate for the transportation of carbon dioxide out of the human body via the process of respiratory gas exchange.
The hydration reactions undergone by carbon dioxide are quite slow, especially in the absence of a suitable catalyst. However, the presence of the enzyme family known as carbonic anhydrases in the red blood cells increases the reaction rate.
The carbonic anhydrase enzymes work to catalyze the conversion of carbon dioxide and water to the dissociated ions of carbonic acid.
This produces bicarbonate anions which get dissolved in the blood plasma. The catalyzed reaction is reversed in the lungs, resulting in the formation of CO2, which is then exhaled.
Importance of Carbonic Acid in Oceans
The absorption of the excess carbon dioxide in the atmosphere (primarily due to human activities) by the oceans is believed to have caused a shift in the pH of the ocean’s water by approximately -0.1. The absorbed carbon dioxide reacts with ocean water and forms H2CO3. This process is commonly referred to as ocean acidification.