Which valuable byproduct is obtained in the Down's process for extraction of sodium

Options

A. Oxygen
B. Hydrogen
C. Chlorine
D. 1 and 2 both

Answer

To solve the question about the valuable byproduct obtained in the Down's process for extraction of sodium, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Down's Process**:
The Down's process is a method used to extract sodium from molten sodium chloride (NaCl). This process involves the electrolysis of a mixture of molten NaCl and calcium chloride (CaCl2).

**Hint**: Recall that the Down's process is specifically designed to extract sodium and involves electrolysis.

2. **Role of Calcium Chloride**:
Calcium chloride is added to the molten NaCl to lower the fusion temperature. Pure NaCl has a high melting point (around 1080 K), which can damage the electrolysis cell. By adding CaCl2, the melting point is reduced to approximately 870 K, making the process more efficient and preventing corrosion.

**Hint**: Consider why lowering the melting point is important in industrial processes.

3. **Electrolysis Reactions**:
In the Down's cell, electrolysis occurs:
- At the **anode** (oxidation): Chloride ions (Cl⁻) lose electrons to form chlorine gas (Cl₂).
- At the **cathode** (reduction): Sodium ions (Na⁺) gain electrons to form solid sodium (Na).

**Hint**: Remember the basic principles of oxidation and reduction in electrolysis.

4. **Overall Reaction**:
The overall reaction can be summarized as:
\[ 2 \text{NaCl (molten)} \rightarrow 2 \text{Na (solid)} + \text{Cl}_2 \text{(gas)} \]
This indicates that for every two moles of sodium chloride, one mole of chlorine gas is produced as a byproduct.

**Hint**: Look for the products formed during the electrolysis of sodium chloride.

5. **Identifying the Byproduct**:
From the overall reaction, we see that chlorine gas (Cl₂) is generated as a byproduct during the extraction of sodium.

**Hint**: Focus on the products of the electrolysis process to identify byproducts.

### Conclusion:
The valuable byproduct obtained in the Down's process for extraction of sodium is **chlorine gas (Cl₂)**.