What is Acid Base Theory| Definition of acid and base in English

All inorganic compound is classified into three groups: -

(i) Acids
(ii) Bases
(iii) Salts
Different Scientist has given their own concept for the properties of acids, bases, and salts.

Arhenious Concept of Acid and Base:- (According to Arhenious)

Acid: Acids are those substances which give hydrogen ion in its aqueous solutions.
Or, Acid are those substances which have replaceable hydrogen ion (H⁺).
Example:- HClO₄,  H₂CO₃,  H₃PO₄,  H₂SO₄,  HNO₃,  NOH,  H₂SO₃,  H-COOH,  CH₃-COOH,  HNO₂.

Base: Bases are those substances which give hydroxide ion in its aqueous solutions. Or,
Bases are those substances which have replaceable hydroxide ion (OH⁻).
Example:- NaOH, KOH, RbOH, CSOH, Mg(OH)₂, Ca(OH)₂, Ba(OH)₂, Sr(OH)₂, Al(OH)₃, NH₄OH, CaO, MgO, LiOH, Zn(OH)₂ .

Note:-  The base (OH⁻) of the element of the first group are called Alkalies because these bases are completely soluble in water that is completely water-soluble bases are called Alkali. The metals which can found alkali are called as Alkali Metal.
Example:- Li, Na, K, Cs, Rb

• Aqua-Regia: It is a mixture of HCl (75%) and HNO₃ (25%) which has the ability to dissolve hard materials like gold and palladium (Pd).

3 HCl + 1 HNO₃

Bronsted and Lowery concept of Acid and Base:-

Acid: Lowery acid is those substances that can donate a proton.

Base: Base is the type of substance that can accept proton donated by Acid.

Note:- Every acid has a conjugation base while every base has a conjugation acid it means this concept based on a pair of conjugation between acid and base.
Example:-

Acid        Base

NH₄⁺  + Cl⁻

H₃O⁺  + SO₄⁻⁻

HCl⁻  + Br⁻

Acidic Radical: When hydrogen ions are removed from an acid then the radical formed is called as acidic radical.
Example:- Cl⁻, SO₄⁻⁻, PO₄⁻⁻, CO₃⁻⁻, NO₃⁻.

Basic Radical:- When hydroxide ions are removed from a base then the radical formed is called a basic radical.
Example:- NaH₄OH, NaOH,  Mg⁺⁺(OH)₂, Al⁺⁺(OH)₃.

Lewis concept of Acid and Base:- (According to Lewis)

Acid: Those substances which can accept lone pair of an electron is called as Lewis acid.

Lone pair accepter → Lewis acid.

Example:-  AlCl₃,  BCl₃,  BF₃

Base: Those substances which can donate lone pair of an electron is called Lewis  Base.

Example:- CH₃, CH₃ - NH₂, NH₃, C₆H₆

➤Acid is a street name for the compound LSD. So LSD is a hallucinogenic drug so Acid is a hallucinogenic drug.

Properties of Acid:

1. It has a sour taste.
2. It changes blue litmus paper to red color.
3. Acid solutions conduct electricity.
4. Acid is highly corrosive by nature because it has a strong ability to absorb water.
5. Strong acids are strong electrologist it means the aqueous solution of strong acid can conduct electricity.

Properties of Base:

1. It has a bitter taste.
2. Generally base has a property of smoothness like soap or detergent.
3. It changes red litmus paper to blue color.
4. Generally, bases are not Corrosive except NaOH and KOH.
5. Strong bases are strong electrolytes why weak bases are weak electrolytes.

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