a) Blue Crystals of a substance changed their colour on heating in a
closed test tube but regained it after sometime when they were allowed
to cool down. Name the substance and write its formula and explain the
phenomenon involved.
(b) Name the compound whose one formula unit is associated with 10
water molecules. How is it prepared? Give equations of related
reactions. Give two uses of the compound..
Answers
Answer:
a] The substance is hydrated copper sulphate (CuSO4 . 5H2O) which looses its water of crystallization on heating in a closed vessel and so its color changes from blue to white but when the vessel is allowed to cool the water vapor again condensed to for the copper sulphate pentahydrate and the color is regained.
the phenomenon is crystallisation
b]The compound is sodium carbonate decahydrate (Na2CO3.10H2O) also called washing soda.
It is prepared by Solvay process.The reactions involved are:
NaCl + CO2 + NH3 + H2O → NaHCO3 + NH4Cl
2 NaHCO 3 → Na2CO3 + CO2 + H2O
Na2CO3 + 10H20 → Na2CO3.10H2O
The main uses of sodium carbonate are as water softener, food processing aid, pH modifier, swimming pool chemical and electrolyte. It is also used in the manufacture of glass, paper, soaps and detergents, and many other useful chemicals.
Explanation:
Answer:
a] The substance is hydrated copper sulphate (CuSO4 . 5H2O) which looses its water of crystallization on heating in a closed vessel and so its color changes from blue to white but when the vessel is allowed to cool the water vapor again condensed to for the copper sulphate pentahydrate and the color is regained.
the phenomenon is crystallisation
b]The compound is sodium carbonate decahydrate (Na2CO3.10H2O) also called washing soda.
It is prepared by Solvay process.The reactions involved are:
NaCl + CO2 + NH3 + H2O → NaHCO3 + NH4Cl
2 NaHCO 3 → Na2CO3 + CO2 + H2O
Na2CO3 + 10H20 → Na2CO3.10H2O
The main uses of sodium carbonate are as water softener, food processing aid, pH modifier, swimming pool chemical and electrolyte. It is also used in the manufacture of glass, paper, soaps and detergents, and many other useful chemicals.
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