Brönsted base

Brönsted Base

A Brönsted Base, named after the Danish chemist Johannes Nicolaus Brønsted, is a substance that can accept a proton (H+) from another substance. This definition is part of the Brønsted-Lowry acid-base theory, which was proposed independently by Brønsted and English chemist Thomas Martin Lowry in 1923. The theory expanded the Arrhenius theory of acids and bases, allowing for a broader understanding of chemical reactions.

Definition and Examples

According to the Brønsted-Lowry theory, a Brönsted Base is any species that can accept a proton from an acid. This is in contrast to the Arrhenius definition, which defines bases as substances that increase the concentration of hydroxide ions (OH−) in water. Common examples of Brönsted Bases include water (H2O), ammonia (NH3), and the hydroxide ion (OH−).

Mechanism

When a Brönsted Base accepts a proton, it becomes a conjugate acid. This transformation is part of a reversible reaction, where the base and its conjugate acid exist in equilibrium. The strength of a Brönsted Base is often discussed in terms of its ability to bind to or accept a proton. Strong bases, such as the hydroxide ion, are characterized by their complete or nearly complete conversion to their conjugate acids in water, while weak bases, like ammonia, only partially convert.

Applications and Importance

Brönsted Bases play a crucial role in many chemical reactions, including neutralization reactions, where an acid and a base react to form water and a salt. They are also vital in buffer solutions, which resist changes in pH when small amounts of acid or base are added. Understanding the behavior of Brönsted Bases is essential in various fields, including biochemistry, pharmaceuticals, and environmental science.

See Also

• Acid-base reaction theories
• pH
• Titration
• Lewis acids and bases