What ion corresponds to the formula CO32-?

• A. Carbonic acid
• B. Bicarbonate
• C. Carbonate
• D. Acetate

Answer: (C)

The ion represented by the formula CO32- is known as carbonate. This polyatomic ion consists of one carbon atom covalently bonded to three oxygen atoms, and it carries a negative two charge. Carbonate is a fundamental component in various chemical processes and is particularly important in environmental chemistry, forming the basis for carbonate minerals and contributing to the buffering system in biological and ecological contexts.

Carbonates can react with acids to produce carbon dioxide, water, and corresponding salts, which is a key reaction in many biological systems. Understanding the characteristics of carbonate ions helps in comprehending their role in both inorganic chemistry and biological systems, such as in the regulation of blood pH.

In contrast, carbonic acid is the aqueous form of CO2 when dissolved in water, and bicarbonate refers to the HCO3- ion, which is the conjugate base of carbonic acid. Acetate is a completely different ion (C2H3O2−), related to acetic acid. Therefore, the identification of CO32- as carbonate aligns with its chemical structure and behavior in various chemical reactions and contexts.