What is the difference between carbonate and bicarbonate?

Carbonate ions consist of one carbon atom and three oxygen atoms, carrying a -2 charge. The ion has a trigonal planar geometry with a molecular weight of 60 g/mol. The structure of the carbonate ion exhibits resonance stabilization, resulting in a hybrid structure that is the most stable form. The oxygen atoms in the carbonate ion carry a partial negative charge.

Bicarbonate ions, on the other hand, are monovalent anions consisting of one carbon atom, three oxygen atoms, and one hydrogen atom. Upon deprotonation, bicarbonate forms carbonic acid. The ion also adopts a trigonal planar geometry with a molecular weight of 61 g/mol. The resonance structure of bicarbonate involves two oxygen atoms that are not bonded to the hydrogen atom. Bicarbonate is alkaline in nature and is the conjugate acid of the carbonate ion. When it reacts with acids, it releases carbon dioxide.

Key Differences:

1. Charge: Carbonate ions carry a -2 charge, while bicarbonate ions carry a -1 charge.
2. Molecular Weight: Carbonate has a molecular weight of 60 g/mol, whereas bicarbonate, due to the presence of a hydrogen atom, has a molecular weight of 61 g/mol.
3. Alkalinity: In highly alkaline conditions, carbonate ions dominate, whereas in weakly alkaline conditions, bicarbonate ions are more prevalent.
4. Solubility: Carbonate ions are insoluble in water at room temperature and atmospheric pressure, while bicarbonate ions are easily soluble in water at the same conditions.