why does water of crystallization has fixed no. of water molecules?
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It has fixed no of water molecules.Any compound has fixed no of molecules of water of crystallization .
This is because the water chemically combines in proportion .
Hope you got it.Thankq
This is because the water chemically combines in proportion .
Hope you got it.Thankq
Yuvrajpaul:
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Water of crystallization is the fixed amount of water, which is necessary for certain salts to crystallize out from their aqueous solutions. This water makes it possible for them to form crystals, and it is responsible for the shapes of their crystals.
The crystals contain the salts and water combined in definite proportions, and when heated, the water is lost. Example, CuSO4.5H2O (blue crystals) - the crystals are formed by the chemical combination of 1 mole of CuSO4with 5 moles of H2O.
When heated, it looses the water of crystallization (i.e. 5 moles) and forms a white powder, CuSO4. Other examples of salts which crystallize with water are Na2CO3.10H2O (crystallizes with 10 moles of H2O); Na2SO4.10H2O (with 10 moles of H2O) and FeSO4.7H2O (with 7 moles of H2O).
From studies, it is found that the water of crystallization actually form chemical bonds with the positive and negative ions of the salts. Example, in CuSO4.5H2O, 4 moles of H2O are in coordinate bonding with Cu2+, while 1 mole of water forms hydrogen bonding with the SO42-ion. In some hydrated salts however, some of the water do not get attached by chemical bonds, but occupy certain positions in the crystal structure - such water is called lattice water.
An example is the hydrate KAl(SO4)2.12H2O, in which 6H2O molecules are lattice water molecules and the other 6 are water of crystallization because they are attached by coordinate bonds to the aluminium ion. Example: If 0.715 g of a hydrated form of sodium trioxocarbonate(IV) exactly reacts with 50 cm3 of 0.10 M hydrochloric acid, determine the number of moles of water of crystallization present in one mole of the hydrated salt. (Na - 23, C = 12, O = 16, H = 1)
The crystals contain the salts and water combined in definite proportions, and when heated, the water is lost. Example, CuSO4.5H2O (blue crystals) - the crystals are formed by the chemical combination of 1 mole of CuSO4with 5 moles of H2O.
When heated, it looses the water of crystallization (i.e. 5 moles) and forms a white powder, CuSO4. Other examples of salts which crystallize with water are Na2CO3.10H2O (crystallizes with 10 moles of H2O); Na2SO4.10H2O (with 10 moles of H2O) and FeSO4.7H2O (with 7 moles of H2O).
From studies, it is found that the water of crystallization actually form chemical bonds with the positive and negative ions of the salts. Example, in CuSO4.5H2O, 4 moles of H2O are in coordinate bonding with Cu2+, while 1 mole of water forms hydrogen bonding with the SO42-ion. In some hydrated salts however, some of the water do not get attached by chemical bonds, but occupy certain positions in the crystal structure - such water is called lattice water.
An example is the hydrate KAl(SO4)2.12H2O, in which 6H2O molecules are lattice water molecules and the other 6 are water of crystallization because they are attached by coordinate bonds to the aluminium ion. Example: If 0.715 g of a hydrated form of sodium trioxocarbonate(IV) exactly reacts with 50 cm3 of 0.10 M hydrochloric acid, determine the number of moles of water of crystallization present in one mole of the hydrated salt. (Na - 23, C = 12, O = 16, H = 1)
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