According to the Brønsted-Lowry definition, what defines an acid?

The Brønsted-Lowry definition categorizes an acid as a substance that donates protons (H⁺ ions) in a chemical reaction. This perspective emphasizes the role of acids and bases in proton transfer, which is a central concept in acid-base chemistry. When an acid donates a proton to a base, it leads to the formation of a conjugate base, illustrating the dynamic nature of these reactions.

This definition stands in contrast to other concepts where an acid might be defined based on its ability to release hydroxide ions or to simply impact the pH of a solution. For instance, while the creation of hydroxide ions might relate to bases in the Arrhenius definition, it does not accurately encapsulate the broader idea of acidity in the Brønsted-Lowry framework. Similarly, increasing the pH does not intrinsically relate to the acidity of a substance, as acids can lower the pH when introduced to a solution. Thus, the focus on proton donation in defining acids is fundamental to understanding their reactivity and interaction with bases in various chemical contexts.