Do you expect different products in solution when aluminium(III) chloride and potassium chloride treated separately with (i) normal water (ii) acidified water, and (iii) alkaline water? Write equations wherever necessary. ?

When aluminum(III) chloride (AlCl₃) and potassium chloride (KCl) are treated with different types of water—normal, acidified, and alkaline—the products formed can indeed vary. Let's break down what happens in each case for both compounds.

1. Treatment with Normal Water

When aluminum(III) chloride is dissolved in normal water, it hydrolyzes to form aluminum hydroxide and hydrochloric acid:

• AlCl₃ + 3H₂O → Al(OH)₃ + 3HCl

Aluminum hydroxide (Al(OH)₃) is a precipitate that can form under certain conditions, while hydrochloric acid remains in solution. On the other hand, potassium chloride simply dissolves in water without any significant reaction:

• KCl → K⁺ + Cl⁻

2. Treatment with Acidified Water

In acidified water, the presence of additional hydrogen ions (H⁺) affects aluminum(III) chloride differently. The hydrolysis reaction is suppressed due to the increased acidity, and the aluminum ions remain in solution:

• AlCl₃ + H⁺ → Al³⁺ + 3Cl⁻

For potassium chloride, the reaction remains unchanged as it is already a neutral salt:

• KCl → K⁺ + Cl⁻

3. Treatment with Alkaline Water

When aluminum(III) chloride is treated with alkaline water, a different scenario unfolds. The hydroxide ions (OH⁻) from the alkaline solution react with aluminum ions to form aluminum hydroxide, which precipitates out:

• Al³⁺ + 3OH⁻ → Al(OH)₃ (s)

In contrast, potassium chloride remains unaffected by the alkaline conditions, continuing to dissociate in solution:

• KCl → K⁺ + Cl⁻

Summary of Reactions

To summarize, the reactions of aluminum(III) chloride and potassium chloride with different types of water yield distinct products:

• Normal Water: AlCl₃ hydrolyzes, KCl dissolves.
• Acidified Water: AlCl₃ remains as Al³⁺, KCl dissolves.
• Alkaline Water: AlCl₃ forms Al(OH)₃ precipitate, KCl dissolves.

In conclusion, the nature of the water used significantly influences the behavior of aluminum(III) chloride and potassium chloride, leading to different products based on the pH of the solution. Understanding these reactions is crucial in fields like chemistry and materials science, where the properties of compounds can change dramatically with their environment.