Question

The phenomenon of corrosion forms a red layer on copper metal. true or false​

Answer 1

The phenomenon of corrosion forms a green layer on copper metal. Thus, the given statement is false.

Explanation:

• Corrosion is a process of degradation of metals by the action of water, moisture and air.
• It results in deterioration of the metal.
• The metals after corrosion form a more stable compound such as oxides, hydroxides, sulfides and carbonates of the metal.
• When copper is left exposed to atmospheric conditions, it gets corroded and a layer of green colour forms on it.
• The reaction of corrosion of copper is $\[4Cu + {O_2} \to 2C{u_2}O\]$.
• The copper (II) oxide formed as a result of corrosion of copper is green in colour.

Answer 2

The statement is false. The red layer is due to oxidation and not corrosion.

Explanation:

Corrosion is usually defined as the degradation of metals due to an electro-chemical process.

• When exposed to the atmosphere, copper oxidizes, causing normally bright copper surfaces to tarnish.
• After a few years, this tarnish gradually changes to dark brown or black, and finally to green.

• 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 color to the surface of copper metal.

• The reaction is as follows:

$2Cu+H_{2}O +CO_{2} +O_{2}$   →   $Cu(OH)_{2} + CuCO_{3}$

• Red layer on copper is formed due to oxidation of copper. Copper oxide is formed earlier in the process of corrosion. This further reacts with other molecules to form a blue-green color.