What Is a Bicarbonate Ion?

A bicarbonate ion is a negatively charged molecule consisting of one carbon, three oxygen and one hydrogen atom. A bicarbonate ion is an intermediate product formed by the deprotonation of carbonic acid. Bicarbonate is very important to human health.

A bicarbonate ion contains a central carbon atom surrounded by three oxygen atoms with a trigonal planar arrangement. One oxygen shares a single bond with carbon and a single bond with hydrogen. The other two oxygen have a double resonance bond with the carbon atom. The bicarbonate ion is the conjugate base of carbonic acid and it is the conjugate acid of the carbonate ion.

The bicarbonate ion plays an important role in human health. It is an intermediate product in the pH buffering system inside the body. In the bicarbonate buffering system, water and carbon dioxide are in equilibrium with carbonic acid, which in turn is in equilibrium with bicarbonate and a proton. Any disturbance to the system will result in a shift in the equilibrium to one side or the other, allowing the pH of the body to remain stable. This is important because small changes in pH could lead to death.

A bicarbonate ion can form a salt with most alkali metals. The most common salt is sodium bicarbonate, which most people will recognize as baking soda.