CHEMISTRY:
Write the five properties of following compounds:
(1) Alum (b) Blue Vitrol (3) Baking Soda (4) Washing Soda (5) Bleaching Powder
Answers
(1)- Alum:-
They are soluble in water, have a sweetish taste, react acid to litmus, and crystallize in regular octahedra. In alums each metal ion is surrounded by six water molecules. When heated, they liquefy, and if the heating is continued, the water of crystallization is driven off, the salt froths and swells, and at last an amorphous powder remains. They are astringent and acidic.
(2)- Blue Vitriol:-
1. Action of Heat
On heating CuSO4.5H2O loses its water of crystallization and decomposes at 720 o C to give cupric oxide and sulphur trioxide.
2. Action of ammonia
Copper sulphate gives deep blue colour with NH4OH forming complex compound.
CuSO4 + 4NH4OH � [Cu (NH3)4]SO4 + 4H2O
3. Action of KI
When KI is added to a solution of CuSO4, a white precipitate of cuprous iodide is produced.
CuSO4 + 2KI � Cu I2 + K2SO4
2CuI2 � Cu2I2 + I2
4. Action with KCN
A yellow precipitate of cupric cyanide is first formed with KCN and it decomposes to give cyanogen gas.
CuSO4 + 2KCN � Cu(CN)2 + K2SO4
2Cu(CN)2 � Cu2(CN)2 + (CN)2
5.Action of alkalies
With alkalies, a pale blue precipitate of copper hydroxide is formed.
CuSO4 + 2NaOH � Cu(OH)2 + Na2SO4
6. Action with H2S
With H2S it gives a black precipitate of copper sulphide.
CuSO4 + H2S � CuS + H2SO4
(3)- Baking Soda:-
Sodium bicarbonate is an odorless, white crystalline solid or fine powder. It has a slightly alkaline taste. Its density is 2.20 g mL-1 and it decomposes in temperatures above 50 ºC. The decomposition yields to sodium carbonate.
(4)- Washing Soda:-
It is a crystalline solid which is white in color.
It exists as a monohydrated salt (Na2CO3.10H2O), anhydrous salt (Na2CO3) , heptahydrous salt (Na2CO3.7H20) and decahydrate salt (Na2CO3.10H2O).
Sodium carbonate is basic in nature.
It has a melting point of 851°C.
In the presence of heat, it loses its water to form an anhydrous salt (soda ash).
Na2CO3.10H2O →373k Na2CO3.H2O →373k Na2CO3
(5)- Bleaching powder:-
1)Bleaching powder is a white powder which gives a strong smell of chlorine.
2) Bleaching powder is soluble in cold water.
3) Bleaching powder reacts with dilute acids to produce chlorine.