According to Brønsted-Lowry theory, what is a Brønsted-Lowry acid?

In the context of Brønsted-Lowry theory, a Brønsted-Lowry acid is defined as a substance that donates protons (H⁺ ions) during a chemical reaction. This theory focuses on proton transfer as the primary aspect of acid-base reactions.

When a Brønsted-Lowry acid donates a proton, it often results in the formation of a corresponding base, which is called its conjugate base. For example, when hydrochloric acid (HCl) donates a proton, it becomes the chloride ion (Cl⁻), illustrating the acid-base pairing.

This definition is significant because it expands the classical Arrhenius definition of acids (which are limited to substances that produce hydrogen ions in solution) to include a broader range of acid-base interactions that may occur in non-aqueous solutions or gas-phase reactions.

Understanding what constitutes a Brønsted-Lowry acid is essential for predicting how substances will react in various chemical environments, making it a fundamental concept in acid-base chemistry.