Write chemical reactions taking place in the extracion of Aluminium from Bauxite ore .

Options

A. The concentration of ore is done by gravity separation method.
B. molten mixture of aluminium oxide, cryolite or fluorspar is electrolysed
C. impure aluminium is refined by liquation
D. molten aluminium is obtained at cathode while fluorine is liberated at anode.

Explanation

To extract aluminum from bauxite ore, several chemical reactions take place during the process. Here is a step-by-step breakdown of these reactions:

### Step 1: Concentration of Bauxite Ore
Bauxite ore, primarily composed of aluminum oxide (Al₂O₃), is first concentrated. This is typically done using the gravity separation method to remove impurities.

### Step 2: Preparation of the Electrolytic Cell
The concentrated bauxite (Al₂O₃) is mixed with cryolite (Na₃AlF₆) and fluorspar (CaF₂). This mixture is used to improve the conductivity of the aluminum oxide and lower its melting point.

### Step 3: Electrolysis of the Mixture
The molten mixture of aluminum oxide, cryolite, and fluorspar is subjected to electrolysis. The overall reaction during electrolysis can be represented as follows:

\[ 2 \text{Al}_2\text{O}_3 (l) \rightarrow 4 \text{Al} (l) + 3 \text{O}_2 (g) \]

### Step 4: Reactions at the Electrodes
During electrolysis, the following reactions occur at the electrodes:

**At the Cathode (Reduction Reaction):**
\[ \text{Al}^{3+} + 3e^- \rightarrow \text{Al} (l) \]
This reaction indicates that aluminum ions gain electrons to form molten aluminum.

**At the Anode (Oxidation Reaction):**
1. The first reaction:
\[ \text{C} + \text{O}^{2-} \rightarrow \text{CO} + 2e^- \]
2. The second reaction:
\[ \text{C} + 2\text{O}^{2-} \rightarrow \text{CO}_2 + 4e^- \]
These reactions show that carbon from the anode reacts with oxide ions to produce carbon monoxide (CO) and carbon dioxide (CO₂), releasing electrons.

### Step 5: Collection of Aluminum
The molten aluminum collects at the bottom of the electrolytic cell, while the gases (CO and CO₂) are released at the anode.

### Summary of Chemical Reactions:
1. Concentration of Bauxite:
- Gravity separation method (not a chemical reaction, but an important step).
2. Electrolysis Reaction:
- \( 2 \text{Al}_2\text{O}_3 (l) \rightarrow 4 \text{Al} (l) + 3 \text{O}_2 (g) \)
3. Cathode Reaction:
- \( \text{Al}^{3+} + 3e^- \rightarrow \text{Al} (l) \)
4. Anode Reactions:
- \( \text{C} + \text{O}^{2-} \rightarrow \text{CO} + 2e^- \)
- \( \text{C} + 2\text{O}^{2-} \rightarrow \text{CO}_2 + 4e^- \)