Conjugate acid-base pair

Conjugate Acid-Base Pair

A Conjugate acid-base pair consists of two substances related to each other by the donating and accepting of a single hydrogen ion. This concept is a fundamental part of the Bronsted-Lowry acid-base theory, which defines an acid as a proton (hydrogen ion) donor, and a base as a proton acceptor.

Definition

In an acid-base reaction, the acid and base react to form their respective conjugates. The acid loses a proton to become its conjugate base, while the base gains a proton to become its conjugate acid. The conjugate acid-base pair thus consists of the acid and its conjugate base, or the base and its conjugate acid.

Examples

A common example of a conjugate acid-base pair is the ammonia/ammonium pair. In water, ammonia (NH3) acts as a base, accepting a proton from a water molecule to form ammonium (NH4+). The water molecule, having lost a proton, becomes a hydroxide ion (OH-), which is the conjugate base of water.

Importance in Chemistry

Understanding conjugate acid-base pairs is crucial in many areas of chemistry, including analytical chemistry, biochemistry, and environmental chemistry. They play a key role in buffer solutions, which resist changes in pH and are essential in many biological systems and industrial processes.

See Also

• Acid
• Base (chemistry)
• pH
• Buffer solution
• Bronsted-Lowry acid-base theory