During extraction of silver from cyanide process , which of the following is formed ?

Options

A. `Na[Ag(CN)_2]`
B. `Na_2[Ag(CH)_2]`
C. `Na_4[Ag(CN)_2]`
D. None of these

Answer

To solve the question regarding the extraction of silver from the cyanide process, we can break it down into the following steps:

### Step-by-Step Solution:

1. **Identify the Ore**:
The primary ore of silver is argentite (Ag₂S), which is a sulfide ore.

2. **Reaction with Sodium Cyanide**:
When argentite is treated with sodium cyanide (NaCN), a complex is formed. The reaction can be represented as:
\[ \text{Ag}_2\text{S} + 4\text{NaCN} \rightarrow 2\text{Na}_2\text{[Ag(CN)}_2] + \text{Na}_2\text{S} \]
Here, sodium cyanide reacts with silver sulfide to form a soluble complex.

3. **Formation of Silver Cyanide Complex**:
The soluble complex formed is sodium dicyanoargentate(I), represented as:
\[ \text{Na}_2\text{[Ag(CN)}_2] \]
This complex is soluble in water.

4. **Filtration**:
After the reaction, the mixture is filtered to separate the insoluble impurities. The filtrate contains the soluble silver complex.

5. **Reduction to Obtain Silver**:
The next step involves adding zinc (Zn) to the filtrate. Zinc has a lower reduction potential compared to silver, allowing it to reduce the silver complex back to metallic silver:
\[ 2\text{Na}_2\text{[Ag(CN)}_2] + \text{Zn} \rightarrow 2\text{Ag} + \text{Na}_2\text{[Zn(CN)}_2] \]
This reaction results in the precipitation of silver.

6. **Final Products**:
The final products of the reaction are metallic silver (Ag) and sodium zinc cyanide (Na₂[Zn(CN)₂]).

### Conclusion:
During the extraction of silver from the cyanide process, the complex sodium dicyanoargentate(I) \((\text{Na}_2\text{[Ag(CN)}_2])\) is formed.