Copper is very slowly oxidised on the surface in moist air, givinga grcen coating of verdigris is

Options

A. `Cu_2O`
B. `CuCO_3`
C. `Cu(CH_4COO)_(2). Cu(OH)_(2)`
D. `CuSO_(4)`

Answer

To solve the question regarding the oxidation of copper in moist air leading to the formation of a green coating known as verdigris, we can break down the process into several steps:

### Step-by-Step Solution:

1. **Understanding the Reaction**:
Copper (Cu) when exposed to moist air undergoes a slow oxidation process. This means that copper reacts with oxygen (O2) and moisture (H2O) present in the air.

2. **Formation of Copper Compounds**:
The oxidation of copper leads to the formation of copper carbonate (CuCO3) and copper hydroxide (Cu(OH)2). These compounds are responsible for the green color associated with verdigris.

3. **Chemical Equation**:
The overall reaction can be represented as:
\[ 2Cu + O_2 + 2H_2O \rightarrow 2Cu(OH)_2 \]
This can further decompose to form copper carbonate:
\[ Cu(OH)_2 \rightarrow CuCO_3 + H_2O \]

4. **Formation of Verdigris**:
Verdigris is a term used for a green pigment that can be formed when acetic acid (CH3COOH) reacts with copper. The reaction can be represented as:
\[ Cu + 2CH_3COOH \rightarrow Cu(CH_3COO)_2 + H_2 \]
When this compound is exposed to air, it can further react to form the green coating.

5. **Conclusion**:
The green coating on copper, known as verdigris, is primarily due to the formation of copper carbonate and copper hydroxide as a result of the oxidation of copper in moist air.