Arrhenius Theory of Acid and Base

Arrhenius theory particularly focus on the acidic or basic behavior of a substance. As per this theory, the substances that dissociate in water to release hydrogen ions (H⁺) are called acids, whereas the substances that dissociate in water to release hydroxide ions (OH^–) are called bases.

In simple terms, this theory states that acids are hydrogen-containing compounds whereas the bases are hydroxide containing compounds.

Examples of Arrhenius acids include: Hydrochloric acid, Sulfuric acid, and Carbonic acid and the examples of Arrhenius bases include: Sodium hydroxide, Potassium hydroxide, and Magnesium hydroxide.

Read More, Acid, Bases and Salts.

Arrhenius Acid

Arrhenius Acids are the substances that release hydrogen ions (H⁺) in water. Mineral acids like hydrochloric acid (HCl), sulfuric acid (H₂SO₄), and nitric acid (HNO₃) are the most prevalent types of Arrhenius acids. In water, these acids split apart to release hydrogen ions and create hydrated ions.

The general equation of Arrhenius acid undergoing dissociation in water is given by:

HA (aq) → H⁺ (aq) + A^– (aq)

Examples of Arrhenius Acid

• Hydrochloric acid is the most common example of Arrhenius acid. The equation of HCL dissociating in water is given as:

HCl + H₂O → H₃O⁺ + Cl^–

In this reaction, one hydrogen ion (H⁺) is released when hydrochloric acid (HCl) dissociates in water, creating a hydrated hydrogen ion (H₃O⁺). Another name for the hydrated ion is the hydronium ion (H₃O⁺). There is no change in the chloride ion (Cl^–) within the solution.

• Carbonic acid (H₂CO₃) is another important illustration of an Arrhenius acid. When carbon dioxide is dissolved in water, carbonic acid is produced. The equation of this reaction is as follows:

H₂CO₃ + H₂O → H₃O⁺ + HCO₃^–

In this reaction, two hydrogen ions (H⁺) are released when carbonic acid (H₂CO₃) dissociates in water, creating a bicarbonate ion (HCO₃^–).

Arrhenius Base

Arrhenius Base are the substances that release hydroxide ions (OH^–) when dissociated in water. Strong bases like potassium hydroxide (KOH) and sodium hydroxide (NaOH) are the most prevalent Arrhenius bases. In water, these bases separate to produce hydrated ions and hydroxide ions.

The general equation of Arrhenius base undergoing dissociation in water is given by:

BOH (aq) → OH^– (aq) + B^– (aq)

Examples of Arrhenius Base

• Sodium hydroxide is the most common example of an Arrhenius base. The equation of this reaction is given as:

NaOH + H₂O → Na⁺ + OH^– + H₂O

In this reaction, a hydrated sodium ion (Na⁺) and a hydrated hydroxide ion (OH^–) are formed when sodium hydroxide (NaOH) dissociates in water. The hydroxyl ion (OH^–) is another name for the hydrated ion. In the solution, there is no change in sodium ions.

• Ammonia (NH₃) is another example of an Arrhenius base. In water, ammonia slightly dissociates to release hydroxide ions. In water, it separates as follows:

NH₃ + H₂O → NH₄⁺ + OH^–

In this reaction, ammonia (NH₃) breaks down into ammonium ions (NH₄⁺) and hydrated hydroxide ions (OH-) in water.

Note: Sodium hydroxide and other strong bases release a greater quantity of hydroxide ions than ammonia does. Because of this, ammonia is categorized as a weak base by the Arrhenius theory.

Arrhenius Theory introduced in 1887 by Swedish scientist Svante Arrhenius, is used to describe the behavior of acids and bases in aqueous solutions. This theory states that a material that releases hydroxide ions (OH^–) in water is an Arrhenius base, and a substance that releases hydrogen ions (H⁺) in water is an Arrhenius acid.

This article will thoroughly explain the Arrhenius theory, along with instances of Arrhenius bases, Arrhenius acids and Arrhenius theory of electrolytic dissociation.