Extraction of Metals - Result Question 50
####50. Statement $I Al(OH) _3$ is amphoteric in nature.
Statement II $Al-O$ and $O-H$ bonds can be broken with equal ease in $Al(OH) _3$.
(1998)
Passage Based Questions
Passage
Copper is the most noble of the first row transition metals and occurs in small deposits in several countries. Ores of copper include chalcanthite $\left(CuSO _4 \cdot 5 H _2 O\right)$, atacamite $\left(Cu _2 Cl(OH) _3\right)$, cuprite $\left(Cu _2 O\right)$, copper glance $\left(Cu _2 S\right)$ and malachite $\left(Cu _2(OH) _2 CO _3\right)$. However, $80 %$ of the world copper production comes from the ore chalcopyrite $\left(CuFeS _2\right)$. The extraction of copper from chalcopyrite involves partial roasting, removal of iron and self-reduction.
(2010)
Show Answer
Solution:
- $Al(OH) _3$ is amphoteric
$$ \begin{gathered} Al(OH) _3+3 HCl \longrightarrow AlCl _3+3 H _2 O \ \text { Base } \ \underset{\substack{\text { Acid } \ Al(OH) _3}}{ }+NaOH \longrightarrow Na\left[Al(OH) _4\right] \end{gathered} $$
High charge and small size of $Al^{3+}$ makes $Al-O$ and $O-H$ bonds equally ionisable.
