Bronsted-Lowry Concept Of Acids and Bases
The Brønsted-Lowry concept of acids and bases, proposed independently by
Johannes Nicolaus Brønsted and Thomas Martin Lowry in 1923, is one of the
fundamental theories used to describe and understand acid-base reactions in
chemistry. This concept defines acids and bases in terms of the transfer of
protons (H+ ions) between substances.
According to the Brønsted-Lowry theory:
Acids: Acids are substances that can donate a proton (H+) to another substance. In
other words, an acid is a proton donor. When an acid donates a proton, it forms
its conjugate base.
Example: In the reaction HCl (hydrochloric acid) + H2O (water) → Cl- (chloride ion)
+ H3O+ (hydronium ion), HCl donates a proton to water, making it an acid.
Bases: Bases are substances that can accept a proton (H+) from another
substance. In other words, a base is a proton acceptor. When a base accepts a
proton, it forms its conjugate acid.
Example: In the reaction NH3 (ammonia) + H2O (water) → NH4+ (ammonium ion) +
OH- (hydroxide ion), NH3 accepts a proton from water, making it a base.
Conjugate Acid-Base Pairs: In any Brønsted-Lowry acid-base reaction, there are
always two pairs of substances involved: the acid and its conjugate base, as well
as the base and its conjugate acid. These pairs are related by the transfer of a
proton.
Example: In the reaction HCl + H2O → H3O+ + Cl-, the conjugate acid-base pairs are
HCl/Cl- and H2O/H3O+.
The Brønsted-Lowry concept of acids and bases, proposed independently by
Johannes Nicolaus Brønsted and Thomas Martin Lowry in 1923, is one of the
fundamental theories used to describe and understand acid-base reactions in
chemistry. This concept defines acids and bases in terms of the transfer of
protons (H+ ions) between substances.
According to the Brønsted-Lowry theory:
Acids: Acids are substances that can donate a proton (H+) to another substance. In
other words, an acid is a proton donor. When an acid donates a proton, it forms
its conjugate base.
Example: In the reaction HCl (hydrochloric acid) + H2O (water) → Cl- (chloride ion)
+ H3O+ (hydronium ion), HCl donates a proton to water, making it an acid.
Bases: Bases are substances that can accept a proton (H+) from another
substance. In other words, a base is a proton acceptor. When a base accepts a
proton, it forms its conjugate acid.
Example: In the reaction NH3 (ammonia) + H2O (water) → NH4+ (ammonium ion) +
OH- (hydroxide ion), NH3 accepts a proton from water, making it a base.
Conjugate Acid-Base Pairs: In any Brønsted-Lowry acid-base reaction, there are
always two pairs of substances involved: the acid and its conjugate base, as well
as the base and its conjugate acid. These pairs are related by the transfer of a
proton.
Example: In the reaction HCl + H2O → H3O+ + Cl-, the conjugate acid-base pairs are
HCl/Cl- and H2O/H3O+.
