What is an acid defined as in chemistry?

In chemistry, an acid is defined as a substance that donates protons (H+ ions) in an aqueous solution, according to the Brønsted-Lowry theory. This definition emphasizes the behavior of acids in chemical reactions. When an acid donates a proton, it results in the formation of a conjugate base. This ability to donate protons is a fundamental characteristic of acids, and it allows them to react with bases in acid-base reactions.

The concept is crucial because it helps to understand various chemical processes, including neutralization reactions, where acids react with bases to form water and salt, and the roles that acids play in various biological and industrial processes. Recognizing the proton-donating nature of acids is essential for predicting how they will behave in different chemical contexts.