According to texts in the books of inorganic chemistry, bicarbonates are the intermediate form in the deprotonation of carbonic acid. It is a polyatomic anion with HCO3as its chemical formula. Bicarbonates serve an essential biochemical role in the physiological pH buffering based systems.

Structural relationship to carbonic acid and bicarbonate anion


The balance of acid-base composition in maintained and controlled by the capability of the respiratory system to eliminate excess carbon dioxide along with the ability of the kidneys to remove wastes in urine and buffering system which is referred to as the buffering system of bicarbonates. The appropriate availability of bicarbonates is the biggest limiting factor to neutralize acidic waste in the human body, which serves as an antioxidant. Bicarbonates can also be delivered via water, in fact, neither water nor the blood is healthy without them.

Neutralization of acids is based on the existence of buffers. For example, if a weak acid is added to a glass of water that has a zero buffering capacity, the pH drops immediately. But, if the same amount of acid is added to a glass filled with buffered water, the pH remains same as before. The buffer neutralizes the acid and leaves the pH of the solution same. The buffers are typically bicarbonates in water and within the human body.

The bicarbonates buffering systems are composed of weak acid i.e, carbonic acid(H2CO3) and a weak base i.e, bicarbonate(HCO3). When combined, they function to keep the pH of the blood and other internal fluids in a particular range. The carbonic acid in the solution dissociates into hydrogen ions and bicarbonate ions. When the acid is added to a bicarbonate system, the bicarbonate ions reconnect with H+ ions and form carbonic acid again. This reduces the concentration of H+ ion and brings the pH back to its original value. The buffers neutralize acids by eliminating hydrogen ions.

H2CO3 + H2O ↔ H+ + HCO3

Carbonic acid + Water ↔ H+ ion + Bicarbonate


  • While baking bicarbonates like sodium bicarbonate find a role as a  leavening agent.
  • They are used to increase the internal pH of the stomach to counteract the activity of highly acidic digestive juices.

Importance to Human Health

The Bicarbonates provides blood the ability to resist changes in pH. Any minute variations in the pH of blood can disrupt critical metabolic functions. Bicarbonates also contribute in resisting the impacts of acid rain in natural water and other acidic influences. The dramatic swing in pH of streams and rivers can be equally destructive. The ocean is also buffered with bicarbonates and capable of neutralizing the enormous amount of acidic waste.

There is much more bicarbonate compared to carbonic acid (approximate ratio 20:1) under the ideal condition in the human body. This is suitable for organisms that release metabolic waste. The higher concentration of bicarbonate at equilibrium is capable of neutralizing the significant amount of acidity. However, bicarbonates become the limiting factor under stress. Pollution, diet, exercise, and age draws bicarbonates and restricts the body’s capacity to neutralize and eradicate acids.

Practise This Question

The variation of amount of gas absorbed per gram of adsorbent with pressure at different temperatures is given in the adjoining fig. Which of the following is correct relation?