Proton donor

Proton Donor

A proton donor is a chemical entity that donates a proton, also known as a hydrogen ion, in a chemical reaction. This concept is a fundamental aspect of acid-base chemistry, where a proton donor is defined as an acid and a proton acceptor is defined as a base.

Definition

The term "proton donor" originates from the Bronsted-Lowry theory of acids and bases, which was proposed by Johannes Nicolaus Brønsted and Thomas Martin Lowry in 1923. According to this theory, an acid is a substance that can donate a proton to another substance, and a base is a substance that can accept a proton from another substance. This definition expands on the earlier Arrhenius theory, which defined acids as substances that produce hydrogen ions in solution and bases as substances that produce hydroxide ions.

Proton Transfer Reactions

In a proton transfer reaction, a proton donor (acid) and a proton acceptor (base) form a conjugate base and a conjugate acid, respectively. This process is known as protonation when a base accepts a proton, and deprotonation when an acid donates a proton.

Examples

Common examples of proton donors include hydrochloric acid, sulfuric acid, and nitric acid. These strong acids completely dissociate in water to donate protons. On the other hand, weak acids like acetic acid and carbonic acid partially dissociate and donate protons.

Importance in Biological Systems

Proton donors play a crucial role in biological systems. For instance, they are involved in the buffer system of the human body, which helps maintain a stable pH. They also play a key role in the process of cellular respiration, where they contribute to the formation of ATP, the energy currency of the cell.

See Also

• Acid
• Base (chemistry)
• Bronsted-Lowry theory
• Protonation
• Deprotonation