In the following sets of reactants which two sets best exhibit the amphoteric character of Al 2 O 3 . xH 2 O ? Set I Al 2 O 3 · xH 2 O s + OH aq - Set II Al 2 O 3 x · H 2 O s + H 2 O l Set III Al 2 O

Question

In the following sets of reactants which two sets best exhibit the amphoteric character of Al₂O₃. xH₂O ?

$\begin{matrix} Set I & {Al}_{2} O_{3} \cdot {xH}_{2} O_{(s)} + {OH}_{(aq)}^{-} \\ Set II & {Al}_{2} O_{3} x \cdot H_{2} O_{(s)} + H_{2} O_{(l)} \\ Set III & {Al}_{2} O_{3} x \cdot H_{2} O_{(s)} + H_{(aq)}^{+} \\ Set IV & {Al}_{2} O_{3} \cdot {xH}_{2} O_{(s)} + {NH}_{3 (aq)} \end{matrix}$

TestHub · Accepted Answer

For a substance to be called amphoteric, it should be able to react as a base as well as an acid. Hence, when it is reacted with a base, it should act as an acid, and when it is reacted with an acid, it should behave as a base.

The reactions for amphoteric nature of Al₂O₃. x H₂O(s) are

${Al}_{2} O_{3} . x H_{2} O (s) \overset{{OH}_{aq}^{-}}{\to} Al {(OH)}_{4}^{-} aq$
Aluminate anion

${Al}_{2} O_{3} . x H_{2} O (s) \overset{H_{aq}^{+}}{\to} {[Al {(H_{2} O)}_{6}]}_{aq}^{3 +}$ .

[Al(H₂O)₆]³⁺is octahedral complex ion

[Al(OH)₄]^-1tetrahedral at pH = 13

Chemistry - PERIODIC TABLE Question with Solution | TestHub

Options:

Doubts & Discussion