Acid and base

Arrhenius’s theory, Bronsted-Lowry theory, Lewis’s acid-base theory, and everything were covered in this chapter’s exploration of theories of acid and bases chemistry’s various facets. A bitter taste in aqueous solutions, blue staining on litmus paper, and the slickness of the solution are all features of bases. For complete neutralisation, the solution must have no acidic or basic properties when mixed with another water solution that contains the same type of acid or base. In the Bronsted-Lowry definition, an acid is a chemical that contributes protons or takes a pair of valence electrons to create a bond (in the Lewis definition). When two valence electrons are exchanged, a bond is formed between the two elements.

Classification

Organic and inorganic acids and bases can be categorised. Several organic acids are commonly used in food, including citric acid, hydrogen cyanide, lactic acid, and tartaric acid. Pyridine and ethylamine are examples of organic bases. Hydrogen sulphide, phosphoric acid, hydrogen chloride, and sulfuric acid are the most prevalent inorganic acids. For example, sodium hydroxide, sodium carbonate, sodium bicarbonate, calcium hydroxide, and calcium carbonate are the most prevalent inorganic bases.

Strong acids and bases, such as hydrochloric acid and potassium hydroxide, have a high propensity to dissociate in water and become ionised in solution. Theories of acid-base indicators as Weak acids and weak bases, such as acetic acid and ammonia, do not dissociate completely in water; they are referred to as weak acids or weak bases. Strong acids produce a lot of hydrogen ions in solution, while strong bases produce a lot of hydroxide ions in solution and a small number of hydrogen ions. The negative logarithm of hydrogen ion concentration, or pH, is a commonly used notation. As a result of their high conductivity, strong acids and strong bases are excellent electrolytes. Poor electrolytes are the result of weak acids and weak bases.

Acid-Base Theories

Theories of acid-base indicators are defined by a single characteristic, which has been the subject of three different theories: 

• Arrhenius’s theory: 

Arrhenius’ (1903 Nobel Prize in chemistry winner Svante Arrhenius’) theory, Brönsted-Lowry’s (1923’s proton donor theory), and Lewis’s (1923’s electron-pair theory). Each of the three theories has advantages and cons of its own, and they are all beneficial in certain situations. Water can break up and separate some of the acid or base particles as they dissolve in it, creating oppositely-charged ions. According to the Arrhenius theories of acid and bases, if an acid can dissociate in water to give hydrogen ions (H+), it is defined as an acid. If an acid can dissociate in water, it is defined as a base (OH-). Dissociation of hydrochloric acid in water produces the necessary H+ and Cl- ions, respectively. Water dissociates sodium hydroxide (NaOH) to produce the necessary hydroxide ions (OH-) and sodium ions (Na+). Liquid ammonia, for example, can operate as an acid or a base when dissolved in a solvent other than water.

• Brönsted-Lowry, or Proton donor: 

Chemistry physicists Johannes Brönsted and Thomas Lowry coined the term “Brönsted-Lowry theory” to describe acids and bases that can be used in both water-free and water-containing solutions. Acids are characterised as proton donors, whereas bases are described as proton acceptors. Since water, H2O can lose a proton to produce a hydroxide ion (OH-) or accept a proton to generate a hydronium ion (H3O+), it can be regarded as an acid or a base under the Brönsted-Lowry hypothesis.The acid’s conjugate base is when it loses a proton and becomes a proton acceptor.  When a base accepts a proton, it forms what is known as the conjugate acid, which can act as a proton donor. In this case, the hydroxide is the conjugate base of the acid, water, because it loses one proton to produce the ion. Water’s conjugate acid, the hydronium ion, is formed when water absorbs a proton to produce a hydronium ion.

Lewis theory of acid and base : 

Gilbert Lewis, an American scientist, has also proposed a hypothesis that defines acids and bases in a much broader sense. When it comes to Theories of acid-base indicators, according to Lewis’s theory of acid and base hypothesis, an acid is something that can take up two electrons. In contrast, a base is something that can give two electrons back. Ethyl alcohol and boron trifluoride (BF3) are examples of Lewis’s theories of acids and bases.

Conclusion: 

Acids and bases are defined by a single characteristic, which has been the subject of three different Theories of acid-base indicators. Sourness, the ability to make litmus paper red, and the production of hydrogen gas are all common characteristics of acid solutions in water. Weak acids and weak bases do not dissociate completely in water; they are called weak acids or weak bases. Acids and bases can use to create water-free and water-containing solutions. Liquid ammonia, for example, can operate as an acid or a base when dissolved in a solvent other than water.