Hydrogen V

Chemical Properties of water:-
[i] AMPHOTERIC NATURE:-
It has the ability to act as an acid^H it acts as an acid with NH₃ and as a base with well as base

[ii] REDOX REACTIONS INVOLVING WATER:-
Water can be easily reduced to H₂ by highly electropositive metals

[iii] HYDROLYSIS REACTION:- 
Due to high dielectric constant, it has a very strong hydrating tendency .it dissolves many ionic compounds.

[iv] HYDRATES FORMATION:- From the aqueous solutions many salts can be crystallized as hydrated salts. It of different types.

Hard & Soft Water:-

• The water which contains dissolved salts of bicarbonates, sulphates and chlorides of calcium and magnesium is called hard water. Hard water does not produce lather with soap solution.
• Soft water is free from bicarbonates, sulphates and chlorides of calcium and magnesium. It produces lather with soap solution easily. e.g., distilled water, rain water.

Types of hardness:- The hardness of water is of two types:
(i) Temporary hardness

• Due to presence of soluble bicarbonates of calcium and magnesium. 
• Can be removed by simple boiling.

(ii) Permanent hardness
Due to presence of chlorides and sulphates of calcium and magnesium.
Requires treatment of water to remove this type hardness.

• Temporary hardness is also called carbonate hardness & Permanent hardness is also called non-carbonate hardness

Softening of water:- The process of removal of Ca²⁺ and Mg²⁺  ions from water is called softening of water.

Removal of temporary hardness:-
(i) By boiling :

(ii) Clark’s method or calcium hydroxide method :

Removal of permanent hardness:-
(i) By washing soda (Na2CO3.10H2O) treatment:

(ii) By using inorganic cation exchanger (permutit method or Zeolite method): 

Zeolite Settles at bottom
The zeolite can be regenerated by treatment with sodium chloride solution.

(iii) By organic ion exchanger or synthetic resins (ion exchange resins):-
Synthetic resins are the insoluble polymeric solids having giant hydrocarbon network containing reactive acidic or basic groups. These are superior to Zeolitebecause they can remove all types of cations as well as anions present in water. This resulting water is known as demineralised or deionised water.

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