In the Bronsted-Lowry theory, what is the role of an acid?

In the Bronsted-Lowry theory, an acid is defined as a substance that donates protons (H⁺ ions) to other substances. This theory focuses on the transfer of protons during acid-base reactions. When an acid donates a proton, it increases the concentration of H⁺ ions in the solution, which is a key characteristic of acidic behavior.

For example, when hydrochloric acid (HCl) dissociates in water, it donates a proton to water molecules, forming hydronium ions (H₃O⁺) and chloride ions (Cl⁻). This proton donation is what makes the solution acidic.

Understanding this concept is crucial because it differentiates acids from bases within the Bronsted-Lowry framework, where bases are defined as proton acceptors. Thus, recognizing the role of an acid as a proton donor helps in analyzing various chemical reactions, particularly those involving acid-base neutralization.