BrønstedovyLowryho

The Brønsted-Lowry theory, also known as the proton transfer theory, is a chemical definition of acids and bases. Proposed independently by Johannes Nicolaus Brønsted and Thomas Martin Lowry in 1923, this theory provides a broader understanding of acid-base reactions than earlier definitions.

According to the Brønsted-Lowry theory, an acid is a substance that can donate a proton (H+) to another substance. Conversely, a base is a substance that can accept a proton from another substance. This definition emphasizes the role of proton transfer in acid-base chemistry.

When an acid donates a proton, it forms its conjugate base. Similarly, when a base accepts a proton, it forms its conjugate acid. This concept of conjugate acid-base pairs is central to the Brønsted-Lowry theory. For example, in the reaction between hydrochloric acid (HCl) and water (H2O), HCl acts as an acid, donating a proton to H2O, which acts as a base. The products are the chloride ion (Cl-), which is the conjugate base of HCl, and the hydronium ion (H3O+), which is the conjugate acid of H2O.

The Brønsted-Lowry theory applies to reactions in aqueous solutions as well as in non-aqueous solvents. It also encompasses a wider range of substances as acids and bases, including ions and molecules that may not fit the Arrhenius definition of acids and bases. This theory is fundamental to understanding many chemical reactions and equilibria.