Classification of Acids, Bases and Salts
Category : 10th Class
Classification of Acids
Classification on the Basis of the Concentration of Acid
The concentration of acid is the amount of acid dissolved in water. On the basis of concentration acids are of two types:
Concentrated Acid
A concentrated acid has relatively high percentage of hydrogen ions in the aqueous solution.
e.g. Concentrated hydrochloric acid, concentrated sulphuric acid etc.
Dilute Acid
A dilute acid has relatively low percentage of hydrogen ions in water. e.g. dilute hydrochloric acid, dilute sulphuric acid etc.
Classification on the Basis of Strength
The strength of an acid is defined as the amount of hydronium ions furnished by one mole of an acid in water. On the basis of strength acids are of two types: Strong acids and Weak acids.
Strong Acids
Those acids which dissociated almost completely into its ions in their aqueous solution.
e.g. hydrochloric acid, sulphuric acid, nitric acid etc.
\[HC{{l}_{(aq)}}+{{H}_{2}}O\to {{H}_{3}}{{O}^{+}}+C{{l}^{-}}\]
\[HN{{O}_{3}}+{{H}_{2}}O\to {{H}_{3}}{{O}^{+}}+NO_{3}^{-}\]
Weak acids
Those acids which undergo partial dissociation in aqueous solution.
e.g. organic acids like acetic acid, oxalic acid etc.
\[C{{H}_{3}}COOH+{{H}_{2}}O\to C{{H}_{3}}CO{{O}^{-}}+{{H}_{3}}{{O}^{+}}\]
\[{{H}_{3}}C{{O}_{3}}+2{{H}_{2}}O\to 2{{H}_{3}}{{O}^{+}}+C{{O}_{3}}^{2-}\]
Classification on the Basis of Basicity
Basicity of an acid is defined as the number of replaceable hydrogen atoms present in a molecule of acid. Basicity is the number of hydronium ion furnished by one molecule of an acid in water or It is the number of hydroxyl ion with which one molecule of an acid can combine.
On the basis of basicity acids can be classified as:
Monobasic Acids
Those acids whose one molecule furnishes one hydronium ion in aqueous solution.
eg.
\[HCl+{{H}_{2}}O\to {{H}_{3}}{{O}^{+}}+C{{l}^{-}}\]
\[HN{{O}_{3}}+{{H}_{2}}O\to {{H}_{3}}{{O}^{+}}+N{{O}_{3}}^{-}\]
Dibasic Acids
Those acids whose one molecule can furnish two hydronium ion in aqueous solution.
e.g.
\[{{H}_{2}}S{{O}_{4}}+2{{H}_{2}}O\to 2{{H}_{3}}{{O}^{+}}+S{{O}_{4}}^{2-}\]
\[{{H}_{2}}C{{O}_{3}}+2{{H}_{2}}O\to 2{{H}_{3}}{{O}^{+}}+C{{O}_{3}}^{2-}\]
Tribasic Acids
Those acids whose one molecule can furnish three hydronium ion in their aqueous solution.
e.g. \[{{H}_{3}}P{{O}_{4}}+3{{H}_{2}}O\to 3{{H}_{3}}{{O}^{+}}+P{{O}_{4}}^{3-}\]
Classification of Acids on the Basis of their Composition
Oxy Acids
The oxy acids are the acids which contain oxygen.
e.g. Acetic acid \[(CHCOOH)\], Sulphuric acid \[({{H}_{2}}S{{O}_{4}}),\] Nitric acid \[(HN{{O}_{3}})\] etc.
Hydro-Acids
The acids which contain hydrogen and an electronegative element other than oxygen.
e.g. Hydrochloric acid (HCI), hydro-iodic acid (HI), Hydrobromic acid (HBr) etc.
Classification of Bases
Classification of Bases on the Basis of Strength
Strength of the bases depends upon the concentration of the hydroxyl ions in the solution. The bases can be classified as:
Strong Base
The base which dissociates almost completely into its ions in water.
e.g. Sodium hydroxide \[(NaOH)\], Magnesium hydroxide \[[Mg{{(OH)}_{2}}]\]
Weak Base
The base which dissociate partially into its ions of hydroxyl ions, e.g. Ammonium hydroxide \[(N{{H}_{4}}OH),\] Zinc hydroxide \[[Zn{{(OH)}_{2}}]\]
Classification Based on Acidity of Bases
The acidity of a base is the number of hydrogen ions with which one molecule of an acid reacts completely. Or it can also be defined as acidity is the number of hydroxyl ions furnished by one molecule of a base in its aqueous solution. On the basis of acidity bases are classified as:
Monoacidic Base
A base whose one molecule furnishes only one hydroxyl ion in its aqueous solution.
e.g. \[NaOH\to N{{a}^{+}}+O{{H}^{-}}\]
Ammonium Hydroxide: \[N{{H}_{4}}OH\to N{{H}_{4}}^{+}+O{{H}^{-}}\]
Diacidic Base
It is a base whose one molecule furnishes two hydroxyl ions in aqueous solution.
e.g. Calcium Hydroxide: \[Ca{{(OH)}_{2}}\to C{{a}^{2+}}+2O{{H}^{-}}\]
Copper Hydroxide: \[Cu{{(OH)}_{2}}\to C{{u}^{2}}+2O{{H}^{-}}\]
Triacidic Base
It is base whose one molecule furnishes three hydroxyl ions in its aqueous solution.
e.g. Ferric Hydroxide : \[Fe{{(OH)}_{3}}\to F{{e}_{3}}^{+}+3O{{H}^{-}}\]
Aluminium Hydroxide: \[Al{{(OH)}_{3}}\to A{{l}^{3+}}+3O{{H}^{-}}\]
Classification of salts
The salts can be classified as:
Normal Salts
These are the salts formed by complete neutralization of an acid with a base or they do not contain any replaceable hydrogen ion.
e.g. Sodium chloride \[(NaCl),\] Magnesium sulphate \[(MgS{{O}_{4}})\], Potassium nitrate \[(KN{{O}_{3}})\]
These salts are obtained by replacing all the hydrogen ions of an acid by metal ions or ammonium ions.
Acid Salt
An acid salt contains replaceable hydrogen atoms. They are formed by partial or incomplete replacement of hydrogen ions by metal ions or ammonium ions.
e.g. Sodium bicarbonate\[(NaHC{{O}_{3}})\], Sodium bisulphate\[(NaHS{{O}_{4}})\],
Disodium hydrogen phosphate \[(N{{a}_{2}}HP{{O}_{4}})\]
Basic Salt
A basic salt is formed by action of strong base on weak acid. They are obtained by the partial replacement of hydroxyl groups of a diacidic or triacidic base by an acid radical.
e.g. Basic copper carbonate \[CuC{{O}_{3}}\]. \[Cu{{(OH)}_{2}}\], Basic lead carbonate \[PbC{{O}_{3}}\] \[Pb{{(OH)}_{2}}\].
Binary Salt
These salts contain atoms of two elements only.
e.g. Copper chloride : \[CuC{{l}_{2}},\] Ferrous sulphide : \[FeS,\] Aluminium chloride : \[AlC{{l}_{3}}\],
Jernary Salt
These salts contain atom of three elements only.
e.g. Sodium sulphate: \[N{{a}_{2}}S{{O}_{4}},\] Potassium Carbonate: \[{{K}_{2}}C{{O}_{3}}\]
Double Salt
These salts are formed when equimolar solution of two simple salts are mixed and crystallized.
e.g. Potash alum : \[{{K}_{2}}S{{O}_{4}}.\,A{{l}_{2}}{{(S{{O}_{4}})}_{3}}.\,24{{H}_{2}}O,\] Chrome alum : \[{{K}_{2}}S{{O}_{4}}.\,C{{2}_{2}}{{(S{{O}_{4}})}_{3}}\].\[24{{H}_{2}}O\]
These salts furnish simpletons when dissolved in water.
e.g. \[{{K}_{2}}S{{O}_{4}}.\,A{{L}_{2}}{{(S{{O}_{4}})}_{3}}.\,24{{H}_{2}}{{O}_{(aq)}}\to 2{{K}^{+}}+4SO_{4}^{2-}+2A{{l}^{3+}}+24{{H}_{2}}O\]
Mixed Salts
These salt contains more than one acid or basic radical.
e.g. Sodium Potassium Sulphate: \[NaKS{{O}_{4}},\] Potassium Calcium Phosphate:\[KCaP{{O}_{4}}\]
Complex Salts
These salts dissociate in water to give one simple ion and one complexion.
e.g. Potassium ferrocyanide \[{{K}_{4}}[Fe{{(CN)}_{6}}]\]
\[{{K}_{4}}[Fe\,{{(CN)}_{6}}]\,\to \,4{{K}^{+}}+\,{{[Fe{{(CN)}_{6}}]}^{4-}}\]
Sodium argento Cyanide \[Na\,[Ag{{(CN)}_{2}}]\]
\[Na\,[Ag{{(CN)}_{2}}]\,\to \,N{{a}^{+}}+\,[Ag{{(CN)}_{2}}]\]
When hydrogen of an acid are partially neutralized by hydroxyl ion of a base we get:
(a) Normal Salt
(b) Acidic Salt
(c) Basic Salt
(d) Complex Salt
(e) None of these
Answer: (b)
Acetic acid is:
(a) Monobasic Acid
(b) Monoacidic
(c) Tetra basic Acid
(d) Tetra Acidic
(E) None of these
Answer: (a)
Explanation
Mono basic acid acetic acid \[(C{{H}_{3}}COOH)\] has only one replaceable
hydrogen atom so it is monobasic acid \[C{{H}_{3}}COOH\to C{{H}_{3}}CO{{O}^{-}}+{{H}^{+}}\].
Hydrogen chloride gas is an acid because when it is dissolved is water it give:
(a) Hydroxyl ions
(b) Hydronium ions
(c) Salt
(d) Base
(e) None of these
Answer: (b)
What colour change would you observe when few drops of phenolphthalein is added to Aluminium hydroxide solution?
(a) Colourless to pink
(b) Red to blue
(c) Pink to colourless
(d) Pink to yellow
(e) None of these
Which of the following ion is present in acid in greater quantity?
(a) \[{{H}^{+}}\]
(b) \[O{{H}^{-}}\]
(c) \[{{O}^{2-}}\]
(d) All of these
(e) None of these
Answer: (a)
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