Question

Aluminium chloride in acidified aqueous solution forms an ion having geometry:

• A. Square planar
• B. Tetrahedral
• C. Octahedral
• D. Trigonal bipyramidal

Answer 1

The Correct Option is C

To determine the geometry of the ion formed when aluminium chloride is dissolved in an acidified aqueous solution, we need to understand what happens during this chemical process.

Concepts involved:

• Aluminium chloride (\(\text{AlCl}_3\)) acts as a Lewis acid and is highly soluble in water.
• When dissolved in water, especially in an acidic medium, the \(\text{Al}^{3+}\) ion can undergo hydration.
• The coordination number of \(\text{Al}^{3+}\) in aqueous solution is 6 because it is surrounded by six water molecules.

This leads to the formation of a complex ion in solution, namely, \(\text{[Al(H}_2\text{O})_6]^{3+}\).

Geometry deduction:

• The arrangement of these six water molecules around the central \(\text{Al}^{3+}\) ion forms an octahedral geometry, which is characteristic of six-coordinate complexes.
• In octahedral geometry, the central atom is at the center of the octahedron, with ligands at each of the six corners.

Conclusion:

Given the aforementioned chemical facts and reasoning, the ion formed in an acidified aqueous solution of aluminium chloride has an octahedral geometry.

Therefore, the correct answer is Octahedral.

Answer 2

Determine the Complex Ion Formed: In acidified aqueous solution, AlCl₃ forms a complex ion, typically [Al(H₂O)₆]³⁺.
Analyze Geometry: - This complex ion has six ligands (water molecules) coordinated around the central aluminum ion. - Six ligands around a central atom generally form an octahedral geometry.
Conclusion: The geometry of [Al(H₂O)₆]³⁺ is octahedral.