Question

5. Explain the following.
a. Copper vessels turn green with the passage of time.
b. Silver objects turn black and lose their lustre with time
c. Aluminium is a corrosion-resistant metal.

Plzz find the answer ​

Answer 1

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1.Copper metal when exposed to air turns green in colour due to corrosion. When copper vessel is exposed to air in rainy season, the metal reacts with gases and moisture and atmospheric gases to form a mixture of copper carbonate and copper hydroxide. This gives a green colour to the surface of copper metal.

2.Object made of silver becomes black with passage of time due to formation of thin silver sulphide layer on surface by the action of hydrogen sulphide present in air. This is because object made from silver reacts with sulphur present in the atmosphere and forms silver sulphide. So, silver becomes black in colour.

3.The corrosion resistance of aluminum is due to its tendency to form a compact oxide layer over the surface. The oxide formed offers a high resistance to corrosion.

Answer 2

Answer:

1.Copper metal when exposed to air turns green in colour due to corrosion. When copper vessel is exposed to air in rainy season, the metal reacts with gases and moisture and atmospheric gases to form a mixture of copper carbonate and copper hydroxide. This gives a green colour to the surface of copper metal.

2.Object made of silver becomes black with passage of time due to formation of thin silver sulphide layer on surface by the action of hydrogen sulphide present in air. This is because object made from silver reacts with sulphur present in the atmosphere and forms silver sulphide. So, silver becomes black in colour.

3.The corrosion resistance of aluminum is due to its tendency to form a compact oxide layer over the surface. The oxide formed offers a high resistance to corrosion.