Question

What is bicarbonate equilibrium?

Answer 1

The most important buffer for maintaining acid-base balance in the blood is the carbonic acid-bicarbonate buffer. The dissolved carbon dioxide and bicarbonate ion are at equilibrium.

CO​​​​​2 + 2H​​​​​​2​O ⇌H2CO3 + H2O⇌HCO3 ​​​- + H​​​​​3O+

The equilibrium on the right is an acid-base reaction where carbonic acid (H​​​​​​2​​​​​CO3) is the acid and water is the base. The conjugate base for H2CO3 is HCO3- (bicarbonate ion). The equilibrium on the left is the association of the dissolved carbon dioxide with a water molecule to form carbonic acid. This equilibrium favors the CO2 side; hence, the concentration of H2CO3 in solution is very small.

This bicarbonate equilibrium affects the pH of blood by maintaining the concentration of carbon dioxide and bicarbonate under bicarbonate equilibrium in the blood.