acids and bases: The Brönsted-Lowry Theory

Some substances act as acids or bases when they are dissolved in solvents other than water, such as liquid ammonia. The Brönsted-Lowry theory, named for the Danish chemist Johannes Brönsted and the British chemist Thomas Lowry, provides a more general definition of acids and bases that can be used to deal both with solutions that contain no water and solutions that contain water. It defines an acid as a proton donor and a base as a proton acceptor. In the Brönsted-Lowry theory, water, H₂O, can be considered an acid or a base since it can lose a proton to form a hydroxide ion, OH⁻, or accept a proton to form a hydronium ion, H₃O⁺ (see amphoterism). When an acid loses a proton, the remaining species can be a proton acceptor and is called the conjugate base of the acid. Similarly when a base accepts a proton, the resulting species can be a proton donor and is called the conjugate acid of that base. For example, when a water molecule loses a proton to form a hydroxide ion, the hydroxide ion can be considered the conjugate base of the acid, water. When a water molecule accepts a proton to form a hydronium ion, the hydronium ion can be considered the conjugate acid of the base, water.

Sections in this article:

• Introduction
• The Lewis Theory
• The Brönsted-Lowry Theory
• The Arrhenius Theory
• Acid-Base Theories
• Classification
• Properties

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