General Principles and Processes of Isolation of Elements

During the extraction of copper, iron is present in the ore as impurity (FeS). The ore together with a little coke and silica is smelted; FeS present as impurity in the ore is oxidized to iron oxide, which then reacts with silica to form fusible ferrous silicate which is removed as slag. $2FeS+3O_2\to 2FeO+2S{O}_2$ $FeO+Si{O}_2\to \underset{\left(Slag\right)}{FeSi{O}_3}$

When bauxite (\(Al_{2}O_{3}\)) is leached with a hot, concentrated solution of sodium hydroxide (\(NaOH\)), it dissolves to form soluble sodium tetrahydroxoaluminate(III) (or sodium aluminate)
The aluminate solution is then neutralized by passing carbon dioxide (\(CO_{2}\)) gas through it. This induces the precipitation of hydrated aluminum oxide.
$$\begin{gathered} {\mathrm{Al}}_2{\mathrm{O}}_3 \left(\mathrm{s}\right)+ 2\mathrm{NaOH}\left(\mathrm{aq}\right) +3 {\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)\to 2\mathrm{Na}\left[\mathrm{Al}{\left(\mathrm{OH}\right)}_4\right]\left(\mathrm{aq}\right) \\ 2\mathrm{Na}\left[\mathrm{Al}{\left(\mathrm{OH}\right)}_4\right]\left(\mathrm{aq}\right) +{\mathrm{CO}}_2 \left(\mathrm{g}\right)\to {\mathrm{Al}}_2{\mathrm{O}}_3 .{\mathrm{xH}}_2\mathrm{O}\left(\mathrm{s}\right) +2{\mathrm{NaHCO}}_3\left(\mathrm{aq}\right) \\ \mathrm{X} =\mathrm{Na}\left[\mathrm{Al}{\left(\mathrm{OH}\right)}_4\right]\left(\mathrm{aq}\right), \mathrm{Y} ={\mathrm{CO}}_2 \left(\mathrm{g}\right), \mathrm{Z}={\mathrm{Al}}_2{\mathrm{O}}_3 .{\mathrm{xH}}_2\mathrm{O}\left(\mathrm{s}\right) \end{gathered}$$

During the extraction of copper, iron is present in the ore as impurity (FeS). The ore together with a little coke and silica is smelted; FeS present as impurity in the ore is oxidized to iron oxide, which then reacts with silica to form fusible ferrous silicate which is removed as slag. $2FeS+3O_2\to 2FeO+2S{O}_2$ $FeO+Si{O}_2\to \underset{\left(Slag\right)}{FeSi{O}_3}$

Copper pyrites (also called chalcopyrite) is an ore containing both copper and iron. Its chemical formula is CuFeS₂.

• Malachite → CuCO₃·Cu(OH)₂ (copper ore)
• Azurite → 2CuCO₃·Cu(OH)₂ (copper ore)
• Dolomite → CaMg(CO₃)₂ (calcium and magnesium mineral)
• Copper pyrites (Chalcopyrite) → CuFeS₂ (contains both copper and iron)

Answer: D. Copper pyrites