Do acids donate or accept hydrogen ions?

Acids are characterized by their ability to donate hydrogen ions (H⁺) when dissolved in a solution. This concept is fundamental to the Brønsted-Lowry acid-base theory, which defines acids as proton donors. When an acid donates a hydrogen ion, it typically leads to the formation of a conjugate base. For example, when hydrochloric acid (HCl) donates a hydrogen ion, it becomes chloride ion (Cl⁻).

Understanding this property of acids is essential in various chemical reactions, including those that involve acids in biological systems. Such processes include metabolic reactions and enzymatic functions where acids play a crucial role.

In contrast, bases are defined as substances that accept hydrogen ions. This distinction is vital in understanding acid-base reactions and their equilibria. The incorrect options involve notions that do not align with the fundamental characteristics of acids as proton donors, making it clear why the correct choice reflects the true nature of acids in biochemical contexts.