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a) AlCl3 fumes in moist air due to its h...

a) `AlCl_3` fumes in moist air due to its hydrolysis
b) Al metal is stable in dry air because of protective oxide layer.
c) `p pi -p pi` back bonding does not occur in halides of aluminium because of larger size.
d) Anhydrous `AlCl_3` cannot be prepared by heating `AlCl_3 . 6H_2 O`.
Correct statements are

A

a , b only

B

b,c only

C

a,c,d only

D

All of these

Text Solution

AI Generated Solution

The correct Answer is:
To determine which statements about aluminum chloride and aluminum are correct, let's analyze each statement step by step. ### Step 1: Analyze Statement A **Statement A:** `AlCl_3` fumes in moist air due to its hydrolysis. - **Explanation:** Aluminum chloride (AlCl₃) reacts with water in moist air to form aluminum hydroxide and hydrochloric acid. The reaction can be represented as: \[ \text{AlCl}_3 + 3 \text{H}_2\text{O} \rightarrow \text{Al(OH)}_3 + 3 \text{HCl} \] - The hydrochloric acid produced is responsible for the white fumes observed. Therefore, this statement is **correct**. ### Step 2: Analyze Statement B **Statement B:** Al metal is stable in dry air because of the protective oxide layer. - **Explanation:** Aluminum metal reacts with oxygen in the air to form a thin layer of aluminum oxide (Al₂O₃) on its surface. This oxide layer protects the underlying aluminum from further oxidation, making it stable in dry air. Thus, this statement is also **correct**. ### Step 3: Analyze Statement C **Statement C:** `p pi - p pi` back bonding does not occur in halides of aluminum because of larger size. - **Explanation:** In compounds like BF₃, back bonding occurs due to the small size of boron, allowing effective overlap of p orbitals. However, aluminum is larger, and thus, it does not exhibit significant p pi - p pi back bonding in its halides. Therefore, this statement is **correct**. ### Step 4: Analyze Statement D **Statement D:** Anhydrous `AlCl_3` cannot be prepared by heating `AlCl_3 . 6H_2 O`. - **Explanation:** When heating AlCl₃·6H₂O, the reaction produces aluminum hydroxide and hydrochloric acid rather than anhydrous aluminum chloride. The balanced equation is: \[ 2 \text{AlCl}_3 \cdot 6 \text{H}_2\text{O} \rightarrow 2 \text{Al(OH)}_3 + 6 \text{HCl} \] - Since anhydrous AlCl₃ is not produced, this statement is also **correct**. ### Conclusion All four statements (A, B, C, and D) are correct. ### Final Answer The correct statements are: **All of the above (A, B, C, D)**. ---
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