BrønstedLowrysyrabaskemi

The Brønsted-Lowry theory, developed independently by Johannes Nicolaus Brønsted and Thomas Martin Lowry in 1923, provides a fundamental definition of acids and bases. According to this theory, an acid is a substance that can donate a proton (a hydrogen ion, H+), while a base is a substance that can accept a proton. This proton transfer is the central concept.

When an acid donates a proton to a base, a chemical reaction occurs. The acid becomes a conjugate base, and the base becomes a conjugate acid. For example, in the reaction of hydrochloric acid (HCl) with water (H2O), HCl acts as the acid, donating a proton to H2O, which acts as the base. The products are the chloride ion (Cl-), the conjugate base of HCl, and the hydronium ion (H3O+), the conjugate acid of H2O.

The Brønsted-Lowry definition is broader than earlier acid-base theories, such as the Arrhenius definition, which focused on the production of hydrogen ions (H+) and hydroxide ions (OH-) in aqueous solutions. The Brønsted-Lowry theory can be applied to reactions in any solvent, not just water, and explains the behavior of substances like ammonia (NH3) as bases. Ammonia accepts a proton from water to form ammonium ions (NH4+) and hydroxide ions (OH-). This theory also highlights the amphoteric nature of certain substances, like water, which can act as either an acid or a base depending on the reaction.