Anhydrous aluminium chloride is prepared by

Options

A. reaction of HCI and AI metal
B. reaction of dry HCI gas and metal AI metal
C. passing Conc `HNO_(3)` gas over heated AI metal
D. reaction of `AI_(2) O_(3)` with dil. HCI

Explanation

To prepare anhydrous aluminum chloride (AlCl3), we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Anhydrous Aluminum Chloride**:
- Anhydrous aluminum chloride is represented by the formula AlCl3. However, in its dimeric form, it is often referred to as Al2Cl6.

2. **Reaction with Dry HCl**:
- Anhydrous aluminum chloride can be prepared by reacting aluminum metal (Al) with dry hydrogen chloride (HCl). The reaction can be represented as:
\[ 2 \text{Al} + 6 \text{HCl} \rightarrow 2 \text{AlCl}_3 + 3 \text{H}_2 \]
- In this reaction, aluminum reacts with dry HCl to produce anhydrous aluminum chloride and hydrogen gas.

3. **Balancing the Reaction**:
- Ensure that the reaction is balanced. Here, we have 2 aluminum atoms, 6 chlorine atoms from HCl, and the products yield 2 aluminum chloride molecules and 3 molecules of hydrogen gas.

4. **Avoiding Hydrated Forms**:
- It is important to note that if aluminum reacts with moist or hydrated HCl, it will produce hydrated aluminum chloride instead of the anhydrous form. Therefore, using dry HCl is crucial for obtaining anhydrous aluminum chloride.

5. **Conclusion**:
- The correct method to prepare anhydrous aluminum chloride is by the direct reaction of aluminum with dry hydrogen chloride.

### Final Answer:
Anhydrous aluminum chloride is prepared by the reaction of aluminum with dry hydrogen chloride (HCl).

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