Classification of Inorganic Compounds

As we know acids, bases, and salts were identified through the examination of their aqueous solutions.A substance that tastes sour in water, turns blue litmus red, and neutralizes bases is known as an acid. A base is a substance that, when dissolved in water, tastes bitter, turns red litmus blue, or neutralizes acids.

Salt is a non-reactive material whose aqueous solution has no effect on litmus. Furthermore, Liebig claimed that acids are hydrogen-containing molecules that can be replaced by metals.

Acids

Acidity is a distinguishing feature of acids. Acidic chemicals are typically extremely sour. Aside from hydrochloric acid, there are numerous different types of acids in our environment. Citrus fruits like lemons and oranges contain citric and ascorbic acids, but tamarind paste contains tartaric acid.

Indeed, the words “acid” and “acidity” are derived from the Latin word “acidus,” which means “sour.” When you dip blue litmus paper into acid, it becomes red, whereas red litmus paper does not. When acids react with certain metals, they also release dihydrogen.

Bases

Bases turn red litmus paper blue, while blue litmus paper remains blue. They have a bitter taste and a soapy texture to them. Other common bases include sodium bicarbonate, which is used in cooking, and home bleach.

Salts

Aside from sodium chloride, other common salts include sodium nitrate, barium sulfate, and others. When hydrochloric acid (acid) reacts with sodium hydroxide, sodium chloride, often known as common salt, is formed (base). Electrostatic forces hold together a cluster of positively charged sodium ions and negatively charged chloride ions in solid sodium chloride.

Electrostatic forces between opposite charges are inversely proportional to the dielectric constant of the medium. In other words, mixing an acidic and a basic molecule can result in the formation of salts.

The universal solvent, water, has a dielectric constant of 80. As a result, when sodium chloride is dissolved in water, the electrostatic force is reduced, allowing the ions to move freely in the solution. As a result of water hydration, they are also well separated.

Dissociation And Ionization

Ions are separated from an ionic crystal when a solid ionic substance dissolves in water. When a neutral molecule is dissolved in a solution, it undergoes ionization, which is the process by which it degrades into charged ions. The strength of the ionic bonds and the degree of ion solvation dictate the degree of ionization.

The following are the three most important current notions of acids and bases:

The Arrhenius Concept

Acids are substances that produce H⁺ ions when dissolved in water, whereas bases are substances that produce OH^– ions when dissolved in water.

HA → H⁺ + A^– (Acid)

B⁺ + OH^– → BOH (Base)

Acid-base reactions, according to Arrhenius, are distinguished by acids dissociated in aqueous solution to form hydrogen ions (H⁺) and bases dissociation in aqueous solution to form hydroxide (OH^–) ions.

Limitations of The Arrhenius Concept

1.Water is required for the presence of acids and bases. Dry HCl cannot function as an acid. HCl only functions as an acid in water and not in any other solvent.

2.The notion does not explain why chemicals in non-aqueous solvents are acidic or basic.

3.Although reactions involving salt production can occur in the absence of a solvent, the neutralization process is only conceivable for reactions that can occur in aqueous solutions.

4.The acidic nature of some salts in aqueous solution, such as AlCl₃, cannot be explained.

5.To define the fundamental nature of NH₃, a lengthy as well as artificial explanation is required.

Bronsted-Lowry Hypothesis

In 1923, Bronsted and Lowry developed a more comprehensive concept 

of acids and bases. An acid, according to them, is any hydrogen-containing material (molecule, anion, or cation) that may give a proton to another substance, whereas a base is any substance (molecule, cation, or anion) that can absorb a proton from another. As a result, acids are proton donors and bases are proton acceptors.

Consider a reaction in which acids conjugate acid-base pairs.

Acid₁ + Base₂ = Acid₂ + Base₁

H₂O + HCl → H₃O+ + Cl^– 

HCl gives a proton to H₂O in this reaction and is hence an acid. Water, on the other hand, receives a proton from HCl and becomes a base as a result. The H₃O⁺ ions transfer a proton to the Cl^– ion in the reverse process, which at equilibrium proceeds at the same rate as the forward reaction, and so H₃O⁺, an ion is an acid. Cl^– ion is a base because it receives a proton from H₃O⁺ ion.

Conjugate acid-base pairs are acid-base pairs in which the members of the reaction can be produced from each other by the gain or loss of protons.

Limitations of Bronsted Lowry Concept 

1.Bronsted Lowry was unable to explain the reaction that occurred in non-protonic solvents such as COCl₃, SO₂, N₂O₄ and others.

2.It cannot explain the reactions between acidic oxides and basic oxides, which can occur in the absence of a solvent, for example (No proton transfer)

3.Although substances such as BF₃, AlCl₃, and others lack hydrogen and hence cannot contribute a proton, they still function as acids.

Conclusion

We conclude that Acids and bases are used in more locations in today’s society than only scientific laboratories. Acids and bases are present in many aspects of our daily lives, including food digestion, medication, and cleaning agents.