more
common?
4. Give scientific explanation
a. Bleaching powder has the odour of
chlorine,
b. The hard water of a well becomes
soft on adding washing soda to it.
c. Soap forms a precipitate in hard
water
d. The particles of powder are given an
electric charge while spraying them
to form the powder coating
Answers
Answer:
a) Bleaching powder is a yellowish white powder with a strong smell of chlorine. When exposed to air, bleaching powder gives a smell of chlorine. This is because bleaching powder reacts with carbon dioxide from the atmosphere to produce calcium carbonate and chlorine gas.
b) When washing soda (Na2CO3. 10H2O) is added to the hard water, Na2CO3 reacts with the chlorides and sulphates of calcium and magnesium and converts them to insoluble carbonate salts. This changes the hard water into soft water and thus makes it suitable for use.
c) When hard water and soap are mixed, the magnesium ion reacts with soap molecules and forms a solid material called a precipitate, which does not dissolve. This precipitate (soap scum) reduces the ability of the soap to make bubbles.
d) While coating, the powder particles are given a negative electric charge to create an electrostatic force of attraction between the particles and the positively charged metallic object. This electrostatic force of attraction helps the powder particles to adhere to the metallic object strongly.
Answer:
a.Bleaching powder is a yellowish white powder with a strong smell of chlorine. When exposed to air, bleaching powder gives a smell of chlorine. This is because bleaching powder reacts with carbon dioxide from the atmosphere to produce calcium carbonate and chlorine gas.
b.When washing soda (Na2CO3. 10H2O) is added to the hard water, Na2CO3 reacts with the chlorides and sulphates of calcium and magnesium and converts them to insoluble carbonate salts. This changes the hard water into soft water and thus makes it suitable for use.