Bicarbonate vs. Carbonic Acid

What's the Difference?

Bicarbonate and carbonic acid are both chemical compounds that play important roles in maintaining the pH balance in our bodies. Bicarbonate, also known as hydrogen carbonate, is a negatively charged ion (HCO3-) that acts as a buffer to regulate the acidity of bodily fluids. It can accept or donate hydrogen ions to maintain a stable pH level. On the other hand, carbonic acid (H2CO3) is a weak acid formed when carbon dioxide dissolves in water. It can dissociate into bicarbonate ions and hydrogen ions, contributing to the regulation of pH. While bicarbonate primarily acts as a buffer, carbonic acid is involved in the transportation of carbon dioxide in the blood and its subsequent removal through respiration. Overall, both bicarbonate and carbonic acid are crucial in maintaining the acid-base balance in our bodies.


AttributeBicarbonateCarbonic Acid
Chemical FormulaHCO3-H2CO3
StructureOne carbon atom bonded to three oxygen atomsOne carbon atom bonded to two oxygen atoms and one hydrogen atom
Role in BufferingActs as a base to neutralize excess acidActs as an acid to neutralize excess base
FormationFormed from the dissociation of carbonic acidFormed from the hydration of carbon dioxide
Presence in the BodyFound in blood plasma and acts as a major bufferPresent in small amounts in blood and tissues

Further Detail


Bicarbonate and carbonic acid are two important chemical compounds that play crucial roles in various biological and chemical processes. While they are closely related, they have distinct attributes and functions. In this article, we will explore and compare the properties, uses, and effects of bicarbonate and carbonic acid.


Bicarbonate, also known as hydrogen carbonate (HCO3-), is an anion that is formed when carbonic acid (H2CO3) loses a proton. It is a weak base and can act as a buffer in maintaining pH balance in many biological systems. Bicarbonate is soluble in water and forms a mildly alkaline solution. It is also found in various minerals and rocks.

On the other hand, carbonic acid is a weak acid that is formed when carbon dioxide (CO2) dissolves in water. It is a diprotic acid, meaning it can donate two protons. Carbonic acid is unstable and readily decomposes into water and carbon dioxide. It plays a crucial role in the carbon dioxide transport system in the human body.


Bicarbonate has numerous uses in various industries and applications. In the food industry, it is used as a leavening agent in baking, helping dough rise and creating a light texture in baked goods. Bicarbonate is also used in the production of effervescent tablets and antacids, where it helps neutralize excess stomach acid. Additionally, it is utilized in water treatment processes to adjust pH levels and remove impurities.

Carbonic acid, although unstable, has important uses as well. It is commonly used in the carbonation of beverages, providing the characteristic fizziness in carbonated drinks. Carbonic acid is also utilized in the oil and gas industry for well stimulation and acidizing processes. Furthermore, it plays a crucial role in the regulation of blood pH in the human body.

Effects on the Human Body

Bicarbonate is an essential component in the human body's acid-base balance. It acts as a buffer, helping to maintain the pH of bodily fluids within a narrow range. Bicarbonate ions are present in the blood and play a vital role in neutralizing excess acid, preventing acidosis. They also assist in the transport of carbon dioxide from tissues to the lungs for elimination.

Carbonic acid, as mentioned earlier, is involved in the regulation of blood pH. It is formed when carbon dioxide produced by cells combines with water in the blood, resulting in the formation of carbonic acid. This acid dissociates into bicarbonate ions and hydrogen ions, which help maintain the blood's pH at a slightly acidic level. The balance between carbonic acid and bicarbonate is crucial for proper physiological functioning.

Chemical Reactions

Bicarbonate and carbonic acid are involved in various chemical reactions. Bicarbonate can react with acids to form carbonic acid, which then decomposes into water and carbon dioxide. This reaction is commonly observed when baking soda (sodium bicarbonate) is combined with an acid, resulting in the release of carbon dioxide gas and the expansion of dough.

Carbonic acid, on the other hand, can undergo a reverse reaction, where it dissociates into bicarbonate ions and hydrogen ions. This reaction is important in the lungs, where carbonic acid is converted back into carbon dioxide and water, allowing for the elimination of carbon dioxide through exhalation.

Environmental Impact

Bicarbonate and carbonic acid can have different effects on the environment. Bicarbonate ions are naturally present in many bodies of water and can act as a buffering agent, helping to maintain stable pH levels. However, excessive amounts of bicarbonate can lead to water alkalinity, which can have negative impacts on aquatic life, such as reduced oxygen availability and impaired nutrient uptake.

Carbonic acid, in the form of dissolved carbon dioxide, plays a significant role in ocean acidification. Increased carbon dioxide levels in the atmosphere lead to higher concentrations of carbonic acid in seawater, resulting in a decrease in pH. This acidification poses a threat to marine organisms, particularly those with calcium carbonate shells or skeletons, as it can hinder their ability to build and maintain their protective structures.


Bicarbonate and carbonic acid are closely related compounds with distinct properties, uses, and effects. Bicarbonate acts as a buffer and is utilized in various industries, while carbonic acid is involved in the regulation of blood pH and has applications in carbonation and oil and gas processes. Understanding the attributes of these compounds is essential for comprehending their roles in biological systems, industrial processes, and environmental impacts.

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