A conjugate acid, within the Brønsted–Lowry acid–base theory, is a species formed by the reception of a proton (H) by a base—in other words, it is a base with a.

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assam On the other hand, a conjugate base is what is left over after an acid has donated a proton during a chemical reaction. Hence, a conjugate base is a species formed by the removal of a proton from an acid.

A cation can be a conjugate acid, and an anion can be a conjugate base, basz on which substance is involved and which acid—base theory is the viewpoint. The simplest anion which can be a conjugate base is the solvated electron whose conjugate acid is the atomic hydrogen.

Conjugate acid

In an acid-base reactionan acid plus a base reacts to form a conjugate base plus a conjugate acid:. Conjugates are formed when an acid loses a hydrogen proton or a base gains a hydrogen proton. Refer to the following figure:. We say that the water molecule is the conjugate acid of the hydroxide ion after the latter received the hydrogen proton donated by ammonium.

Conjugate acid – Wikipedia

On the other hand, ammonia is the conjugate base for the acid ammonium after ammonium has donated a hydrogen ion towards the production of the water molecule. Based on this information, it is clear that the terms “Acid”, “Base”, “conjugate acid”, and “conjugate base” are not fixed for a certain chemical species; but are interchangeable according to the reaction taking place.

The strength of a conjugate acid is directly proportional to its dissociation constant. If a gasa acid is strong, its dissociation will have a higher equilibrium constant and the products of the reaction will be favored. The strength of a lodry base can be seen as the tendency of the species to “pull” hydrogen protons towards itself.


If a conjugate base is classified as strong, it will “hold on” to the hydrogen proton when in solution and its acid will not dissociate. On the other hand, if a species is classified as a strong acid, its conjugate base will be weak in nature. An example of this case would be the dissociation of Hydrochloric acid HCl in water.

Similarly, if an acid is weak, its conjugate base will be strong. Therefore, weak acids will have weak conjugate bases, unlike the misconception that they have strong conjugate bases. The acid and conjugate base as well as the base and conjugate acid are known as conjugate pairs.

When finding a conjugate acid or base, it is important to look at the reactants of the chemical equation. In this case, the reactants are the acids and bases, and the acid corresponds to the conjugate base on the product side of the chemical equation; as does the base to the conjugate acid on the product side of the equation. To identify the conjugate acid, look for the pair of compounds that are related.

The acid—base reaction can be viewed in a before and after sense. The before is the reactant side of the equation, the after is the product side of the equation. The conjugate acid in the after side of an equation gains a hydrogen ion, so in the before side of the equation the compound that has one less hydrogen ion of the conjugate acid is the base. The conjugate base in the after side of the equation lost a hydrogen ion, so in the before side of the equation, the compound that has one more hydrogen ion of the conjugate base is the acid.

One use of conjugate acids and bases lies in buffering systems, which include a buffer solution.

In a buffer, a weak acid and its conjugate base in the form of a saltbaea a weak base and its conjugate acid, are bronstex in order to limit the pH change during a titration process. Buffers have both organic and non-organic chemical applications. For example, besides buffers being used in lab processes, our blood acts as a buffer to maintain pH.


The most important buffer in our bloodstream is the carbonic acid-bicarbonate bufferwhich prevents drastic pH changes when CO 2 is introduced.

This functions as such:. A second common application with an organic compound would be the production of a buffer with acetic acid. Acetic acid, along with many other weak acids, serve as useful components of buffers in different lab settings, each useful within their own pH range.

Lactic acid has the formula C 3 H 6 O 6 and its conjugate base is used in intravenous fluids that consist of sodium and potassium cations along with lactate and chloride anions in solution with distilled water. These fluids are commonly isotonic in relation to human blood and are commonly used for spiking up the fluid level in a system after severe blood loss due to trauma, surgery, or burn injury.

Acid strength decreases and conjugate base strength increases down the table. In contrast, here is a table of bases and their conjugate acids. Similarly, base strength decreases and conjugate acid strength increases down the table. From Wikipedia, the free encyclopedia. Retrieved from ” https: Views Read Edit View history. This page was last edited on 30 Julyat By using this site, you agree to the Terms of Use and Privacy Policy. H 2 SO 4 Sulfuric acid. H 2 O Water.

H 3 PO 4 Phosphoric acid. H 2 CO 3 Carbonic acid. H 2 S Hydrosulfuric acid. C 2 H 5 NH 2 Ethylamine. CH 3 NH 2 Methylamine. C 5 H 5 N Pyridine. C 6 H 5 NH 2 Aniline. C 6 H 6 CO 2 Benzoic acid. H 2 O Water neutral, pH 7.