Acids, Bases and Salts


   
 
More about Salts

Generally, salts are obtained by treating an acid with a base. Salts consist of both positive ions or 'cations', and negative ions or 'anions'. The cations are called basic radicals and are mostly obtained from metallic ions (ammonium ion being one exception), while the anions are called acidic radicals and are obtained from acids.

image

Salt is a compound, which on dissociation in water yields positive ions other than a hydrogen ion or hydronium ion, and a negative ion other than hydroxyl ion.

image

Family of Salts
Salts can be classified into the following types:

Normal or Neutral Salts
A salt that does not contain any replaceable hydrogen ions is a normal salt. It is obtained by replacing all the hydrogen ions of an acid by metal ions or ammonium ions. 

Examples: NaCl, Na2SO4, Na3PO4, NH4Cl, K2CO3, CuSO4 etc.

Bisalts or Acid Salts
A bisalt or an acid salt contains replaceable hydrogen ions in association with the acidic radicals. It is obtained by the incomplete replacement of hydrogen ions by metal ions or ammonium ions.

Examples: NaHCO3, NaH2PO4 and Na2HPO4.

Since such salts also contain hydrogen ion, the term 'bi' or acid can be substituted by hydrogen, e.g. sodium bicarbonate or sodium acid carbonate is also called sodium hydrogen carbonate.

When bisalts or acid salts dissociate in water, they yield hydrogen or hydronium ions.

imageimageimage

image

i) An acid salt reacts with bases to form salt and water only.

ii) image

iii) They react with carbonates to yield carbon dioxide.

image

Remember
Some Common Acid Salts
NaHCO3, NaHSO3, NaHSO4, Na2HPO4, Ca(HCO3)2, Ca(HSO4)2, KHCO3, KHSO3, KHSO4, NaH2PO4and Mg(HCO3)2

Basic Salts
A basic salt is formed when there is a higher proportion of the base in the reaction between an acid with a base, than is necessary for the formation of a normal salt.

Example:

Basic copper carbonate CuCO3.Cu(OH)2

Basic lead carbonate (white lead) PbCO3.Pb(OH)2

Double Salts
Such salts are formed by the intimate association of two simple salts, when crystallized from a solution of a mixture of the two.

Some Common Double Salts
Potassium alum image
Ammonium alum image
Ferric ammonium alum image
Potassium chromium alum image

Mixed Salts
Salts that contain more than one acid radical or basic radical are called as mixed salts.

Some Common Mixed Salts
Potassium calcium phosphate image
Bleaching powder image
Sodium potassium carbonate image
Sodium potassium sulphate image

Complex Salts
Salts that dissociate in water to give one simple ion and one complex ion are called complex salts.

image

image

image

image

 
 
     
Get FREE Live Tutoring
Get FREE Live Tutoring
(No credit card required)