When Alumina is electrolysed in presence of cryolite, the gas liberated at graphite anode is

Options

A. `F_(2)`
B. `O_(2)`
C. `CF_(4)`
D. `CI_(2)`

Answer

To solve the question regarding the gas liberated at the graphite anode during the electrolysis of alumina in the presence of cryolite, we can follow these steps:

### Step 1: Understand the Electrolysis Process
Electrolysis involves the breakdown of a compound into its elements using electricity. In this case, we are looking at alumina (Al2O3) being electrolyzed.

**Hint:** Recall that electrolysis requires a conductive medium and involves the movement of ions towards electrodes.

### Step 2: Identify the Components
In this process, alumina is mixed with cryolite (Na3AlF6) to lower the melting point and improve conductivity. Cryolite helps in dissolving alumina and allows the electrolysis to occur at a lower temperature.

**Hint:** Consider why cryolite is used in the process and how it affects the melting point of alumina.

### Step 3: Determine the Reactions at the Electrodes
During electrolysis:
- At the anode (positive electrode), oxidation occurs. In the case of alumina, oxygen ions (O^2-) are oxidized to form oxygen gas (O2).
- At the cathode (negative electrode), aluminum ions (Al^3+) are reduced to form liquid aluminum.

**Hint:** Remember the general rule that oxidation occurs at the anode and reduction occurs at the cathode.

### Step 4: Identify the Gas Released
From the reactions, we can conclude that oxygen gas is produced at the anode. This oxygen can react with the carbon of the graphite anode to form carbon monoxide (CO) or carbon dioxide (CO2), but the primary gas liberated is O2.

**Hint:** Think about the products formed during the oxidation of oxygen ions.

### Step 5: Conclusion
Based on the above analysis, the gas liberated at the graphite anode during the electrolysis of alumina in the presence of cryolite is oxygen gas (O2).

**Final Answer:** The correct option is **Option 2: O2**.

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