Coz it Reacts in gases and moisture and atmospheric gases to form a mixture of copper carbonate and copper hydroxide. This gives a green colour to the surface ofcopper metal.

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Introduction:

Copper is a metallic element that is widely used in the production of various objects, including vessels, due to its excellent conductivity and corrosion resistance. However, when exposed to air, especially during the rainy season, copper vessels tend to develop a greenish coat on their surface. This phenomenon is known as copper patina or copper oxide.

Explanation:

1. Oxidation Process:
When copper is exposed to air, it undergoes an oxidation process. This means that the copper atoms react with oxygen molecules in the air to form copper oxide. The presence of moisture in the rainy season accelerates this oxidation process.

2. Formation of Copper Oxide:
The greenish coat that forms on the surface of copper vessels is primarily composed of copper(II) oxide (CuO) and copper(II) carbonate (CuCO3). These compounds are formed as a result of the reaction between copper and oxygen in the air.

3. Chemical Reactions:
The oxidation of copper can be described by the following chemical reactions:

2Cu + O2 → 2CuO
CuO + CO2 + H2O → CuCO3 + H2O

4. Factors Influencing the Green Coat:
Several factors influence the rate at which the green coat forms on copper vessels during the rainy season. These include:

- Humidity: High levels of humidity provide moisture, which accelerates the oxidation process.
- Temperature: Higher temperatures increase the rate of chemical reactions, including the oxidation of copper.
- Air Pollution: The presence of certain pollutants in the air, such as sulfur dioxide, can speed up the formation of the green coat.
- Exposure Time: The longer the copper vessels are exposed to air, the thicker and more pronounced the green coat becomes.

5. Protective Layer:
Although the green coat may appear unsightly to some, it actually serves as a protective layer for the underlying copper. Copper oxide acts as a barrier, preventing further oxidation and corrosion of the copper surface.

6. Aesthetic Appeal:
Interestingly, the greenish patina that develops on copper vessels is often considered aesthetically pleasing. It is commonly associated with antique copper objects and is often intentionally induced through various chemical treatments to achieve a desired vintage or aged look.

Conclusion:
In conclusion, the green coat that forms on copper vessels when exposed to air during the rainy season is a result of the oxidation of copper. This process, accelerated by moisture and other factors, leads to the formation of copper oxide compounds. While it may alter the appearance of the copper, the green coat provides a protective layer and is often appreciated for its aesthetic appeal.