More about salts

Explain the different products formed during electrolysis of sodium chloride (NaCl) in solution & in fused state.

Ans. i) Electrolysis of aqueous solution of NaCl when electricity is passed through an aqueous solution of sodium chloride commonly known an brine (10% NaCl), it decomposes to form sodium hydroxide. Chlorine (Cl₂) gas is liberated at anode & hydrogen (H₂) gas at cathode respectively.

2NaCl + 2H₂O  ------->  2NaoH + C2 + H₂

ii) Electrolysis of fused sodium chloride : When sodium chloride is heated at high temperature, it melts. The moten state is termed as fused state. NaCl in fused state conducts electricity. During electrolysis Cl₂ (g) is liberated at anode & sodium is deposited at the cathode.

2NaCl   ------->  2Na + Cl2 

Give the properties of NaCl with its uses.

Ans. Properties of NaCl.

i) Impure NaCl is brown in colour known as rock salt & purified NaCl is white (colourless), crystalline ionic compound.

ii) It is soluble in water.

Uses of NaCl.

i) NaCl is an essential constituent of our daily life. It is used in food items.

ii) It is used in the preparation of baking soda (NaHCO₃) & washing soda (Na₂CO₃).

State applications of baking soda [(NaHCO₃) sodium bicarbonate]

Ans. i) Baking soda also called as sodium bicarbonate, has many appliances.

ii) It is used in the preparation of light, soft & spongy breads, cakes & dhokla.

iii) It is used to treat slightly alkaline hyperactivity, i.e. acidity in the stomoch.

iv) Its solution is used in fire, extinguishers to produce carbon dioxide & water.

How bleaching powder is prepared?

Ans. When dry slaked lime reacts with chlorine gas, it gives bleaching powder.

Ca(OH)2     +    Cl₂       ------->             CaOCl₂      +    H2O

Slaked lime   chlorine             Bleaching powder

State two properties of bleaching powder.

Ans. i) Bleaching powder is a white powder with strong odour of chlorine gas.

ii) It is an oxidizing agent in many chemical reactions.

Give uses of bleaching powder (CaOCl₂)

Ans. i) Bleaching powder (CaOCl₂) is used to disinfect a place which is not clean.

ii) It is also used to  disinfeet water.

iii) It is used for bleaching cotton in the textile industry, wood pulp in paper factories & washed clothes in laundry.

iv) It is used in the preparation of chloroform.

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