bicarbonateacid

Bicarbonate acid is not a standard term in chemistry. In most contexts, it informally refers to carbonic acid, H2CO3, the weak diprotic acid formed when carbon dioxide dissolves in water. The bicarbonate ion, HCO3−, is the conjugate base of carbonic acid and an important component of the carbonic-bicarbonate buffering system.

Formation and acidity: In aqueous solution, CO2(g) dissolves and hydrates: CO2 + H2O ⇌ H2CO3. Carbonic acid partially dissociates: H2CO3 ⇌ H+ + HCO3− (pKa1 about 6.35). The bicarbonate ion can further dissociate: HCO3− ⇌ H+ + CO3^2− (pKa2 about 10.33). At physiological pH (~7.4) the dominant species are HCO3− and CO2/H2CO3, enabling buffering in biological systems.

Role and significance: In biology, the bicarbonate/carbonic acid system maintains blood pH and facilitates CO2 transport; kidneys and lungs regulate this balance. In geology and environmental science, carbonic acid forms when CO2 dissolves in rainwater and in oceans, lowering water pH and contributing to weathering and the dissolution of carbonate minerals.

Applications and safety: Sodium bicarbonate (baking soda) and related bicarbonates are common bases used in food preparation, medicine, fire suppression, and cleaning. Carbonic acid itself is unstable in pure form and exists mainly in solution as dissolved CO2; it decomposes to CO2 and H2O when concentrated. Nomenclature note: the term “bicarbonate acid” is uncommon; sources typically use “carbonic acid” for H2CO3 and “bicarbonate” for HCO3−.