Acid
The term Acid is derived from Latin word “Acidus” meaning sour taste.
Example:
Lemon, unripen grapes , vinegar, tomato, orange etc
“Acid are those substance that sour taste, and are corrosive in nature .”
- Many food item such as lemon, curd vinegar, and orange taste are sour because of the presence of acid in them.
- Change the colour the blue litmus to red.
According to Arrhenius theory:
In 1884 Arrhenius said that, an acid is substance which dissolved in water it ionizes and release hydrogen ion ( H+ (aq.) ) in solution.
Hydrogen ion do not occur as H+ ion in solution they attached themselves to polar water molecules and form hydronium ion or hydroxonium ion ( H3O+ ).
Classification of acid :
I) On the basis of their source acid are two type i) inorganic acid(mineral acid) ii) organic acid.
i) Inorganic Acid ( Mineral Acid) :
The acid which are obtained from mineral are known as inorganic Acid.
Example:
Hydrochloric Acid ( HCl) present in our stomach, Sulphuric Acid ( H2SO4) present in car batteries, phosphoric Acid (H3PO4) use for flavouring, Nitric Acid ( HNO₃) explosive, Carbonic Acid (H2CO3) etc.
ii) Organic Acid:
The acid which are usually obtained from plant and animals are known as Organic Acid.
Example: Different acid and their source
Sr. No. |
Acid | Source |
1. |
Lactic acid |
Curd |
2. | Oxalic acid |
Spinach, tomato |
3. |
Malic acid | Apple |
4. | Citric acid |
Lemon, orange |
5. |
Tartaric acid | Tamarind, grape, mango |
6. | Formic acid |
Ant’s sting |
7. |
Acetic acid | vinegar (8% in water) |
8. | Ascorbic acid |
Amla |
II) On the basis of their Basicity:
The basicity of acid is the number of hydrogen ions, which can be produced by one molecule of the acid.
On the basis of Basicity these are three types i) Monobasic acid ii) Dibasic acid iii) tribasic acid.
i) Monobasic acid:
The acid an complete ionization produce on hydronium ion in aqueous solution. Or one hydronium ion present in acid compound.
Example:
HCl ( H+ Cl–) , HBr, HI, HF, CH3COOH, etc.
ii) Dibasic acid:
The acid On complete ionization and produced two hydronium ion in aqueous solution.
Example:
H2SO4 , H2CO3 , etc.
iii) Tribasic acid:
The acid on complete ionization and produces three hydronium ion in aqueous solution.
Example:
H3PO4, H3PO3 etc.
III) On the basis of their strength:
Classification on the basis of their strength are two type i) strong acid ii) weak acid
i) Strong Acid:
The acid which undergoes complete ionization in aqueous solution are known as strong acid.
Strength of acid is directly proportional to the concentration of H+ ion.
Example: H2SO4, HCl, HBr, HNO₃ , HI etc.
ii) Weak Acid:
The acid which undergoes partial or incomplete ionization in aqueous solution are known as weak acid.
Example:
HCOOH, H3PO4, H3PO3 , H2CO3, CH3COOH etc.
IV) On the basis of concentration of acid:
Classification on the basis of concentration of acid are two type; i) concentrated acid ii) dilute acid.
i) Concentrated acid:
The acid which contains large amount of acid and small or minor amount of water are called concentrated acid.
ii) Dilute acid:
The Acid which contains more amount of water in acid is called dilute acid.
Note: Mixing of acid and water is highly exothermic process :
- When water is added into acid , evolved heat will change it into vapour and acid will spill out and may cause injury.
- So it is advice to mix acid into water slowly .
- Not water to acid.
Question answer:
1) What is acid?
2) What is Arrhenius Theory?
3) Give the classification of acid on the basis of their strength?
4) Give the classification of acid on the basis of their basicity?
5) What is basicity of acid?