Exams › JEE Advanced › Chemistry

The aluminium ion, $\mathrm{Al^{3+}}$, has a high positive charge and a large charge density. This polarizes water molecules in $[\mathrm{Al(H_2O)_6}]^{3+}$, weakening the O–H bond and releasing $\mathrm{H^+}$ ions. Which of the following best describes the resulting solution?

1. A solution with strong basic properties
2. A solution with weak acidic properties
3. A solution with strong acidic properties
4. A solution with weak basic properties

Correct answer: A solution with weak acidic properties

Solution

The hexaaquaaluminium(III) ion undergoes hydrolysis because the highly charged $\mathrm{Al^{3+}}$ polarizes coordinated water molecules. This releases $\mathrm{H^+}$ ions, making the solution acidic; in standard chemistry it is considered weakly acidic.

Related JEE Advanced Chemistry questions

• In water, the aluminate species \([Al(H_2O)_6(OH)_4]\) forms, indicating that aluminum's coordination number is 6. What is the nature of this species?
• Consider the following complex ions, P, Q and R: P = [FeF₆]³⁻, Q = [Fe(H₂O)₆]³⁺, and R = [Fe(H₂O)₆]²⁺. The correct order of the complex ions according to their spin-only magnetic moment values (in B.M.) is:
• The pair of coordination complexes/ions exhibiting the same kind of isomerism is:
• Which of the following is the reagent?
• A $0.01$ molal solution of a cobalt(III) chloride-ammonia complex, which dissociates completely, has a freezing point of $-0.0558^\circ\text{C}$. Based on this data, how many chloride ions are present within the coordination sphere of the complex? [$K_f$ for water $=1.86\ \text{K kg mol}^{-1}$]
• Among $[Ni(CO)_4]$, $[NiCl_4]^{2-}$, $[Co(NH_3)_4Cl_2]Cl$, $Na_3[Co(C_2O_4)_3]$, $Na_2O_2$, and $CsO_2$, the total number of paramagnetic compounds is:

⚔️ Practice JEE Advanced Chemistry free + battle 1v1 →