JEE Challenger
More from General Principles and Processes of Isolation of Elements
ChemMedAdv 2008 • Paper 2

Matching Ore Conversions with Metallurgical Reaction Types

Match the conversions in Column I with the type(s) of reaction(s) given in Column II. Indicate your answer by darkening the appropriate bubbles of the 4×44 \times 4 matrix given in the ORS

Column IColumn II(A) PbS→PbO(p) roasting(B) CaCO3→CaO(q) calcination(C) ZnS→Zn(r) carbon reduction(D) Cu2S→Cu(s) self reduction\begin{array}{ll} \textbf{Column I} & \textbf{Column II} \\ \text{(A) } \text{PbS} \rightarrow \text{PbO} & \text{(p) roasting} \\ \text{(B) } \text{CaCO}_3 \rightarrow \text{CaO} & \text{(q) calcination} \\ \text{(C) } \text{ZnS} \rightarrow \text{Zn} & \text{(r) carbon reduction} \\ \text{(D) } \text{Cu}_2\text{S} \rightarrow \text{Cu} & \text{(s) self reduction} \end{array}

Options

A

(A)→(P),  (B)→(Q),  (C)→(R),  (D)→(P,S)(\text{A}) \rightarrow (\text{P}),\; (\text{B}) \rightarrow (\text{Q}),\; (\text{C}) \rightarrow (\text{R}),\; (\text{D}) \rightarrow (\text{P}, \text{S})

B

(A)→(P,Q),  (B)→(Q),  (C)→(P,R),  (D)→(S)(\text{A}) \rightarrow (\text{P}, \text{Q}),\; (\text{B}) \rightarrow (\text{Q}),\; (\text{C}) \rightarrow (\text{P}, \text{R}),\; (\text{D}) \rightarrow (\text{S})

C

(A)→(P),  (B)→(Q,R),  (C)→(P),  (D)→(P,S)(\text{A}) \rightarrow (\text{P}),\; (\text{B}) \rightarrow (\text{Q}, \text{R}),\; (\text{C}) \rightarrow (\text{P}),\; (\text{D}) \rightarrow (\text{P}, \text{S})

D

(A)→(P),  (B)→(Q),  (C)→(P,R),  (D)→(P,S)(\text{A}) \rightarrow (\text{P}),\; (\text{B}) \rightarrow (\text{Q}),\; (\text{C}) \rightarrow (\text{P}, \text{R}),\; (\text{D}) \rightarrow (\text{P}, \text{S})

Correct

Topics & Concepts

General Principles and Processes of Isolation of ElementsMetallurgy

Step-by-Step Solution

To determine the correct matching between the conversions in Column I and the reaction types in Column II, we analyze each metallurgical conversion step-by-step:

  1. (A) PbS→PbO\text{PbS} \rightarrow \text{PbO}:
    The conversion of a sulfide ore like galena (PbS\text{PbS}) to its oxide (PbO\text{PbO}) involves heating the ore strongly in the presence of excess air below its melting point:
    2PbS+3O2→Δ2PbO+2SO2↑2\text{PbS} + 3\text{O}_2 \xrightarrow{\Delta} 2\text{PbO} + 2\text{SO}_2 \uparrow
    This process of heating in excess oxygen is known as roasting.
    Therefore, (A) matches with (p).

  2. (B) CaCO3→CaO\text{CaCO}_3 \rightarrow \text{CaO}:
    The thermal decomposition of calcium carbonate (CaCO3\text{CaCO}_3) into calcium oxide (CaO\text{CaO}) is carried out by heating the ore in the absence or limited supply of air:
    CaCO3→ΔCaO+CO2↑\text{CaCO}_3 \xrightarrow{\Delta} \text{CaO} + \text{CO}_2 \uparrow
    This process of thermal decomposition of carbonates or hydrated oxides without or in limited air is known as calcination.
    Therefore, (B) matches with (q).

  3. (C) ZnS→Zn\text{ZnS} \rightarrow \text{Zn}:
    The extraction of zinc from zinc blende (ZnS\text{ZnS}) involves two essential steps:

    • Roasting: Zinc sulfide is first roasted in air to convert it into zinc oxide:
      2ZnS+3O2→Δ2ZnO+2SO2↑(roasting)2\text{ZnS} + 3\text{O}_2 \xrightarrow{\Delta} 2\text{ZnO} + 2\text{SO}_2 \uparrow \quad \text{(roasting)}
    • Carbon Reduction: Zinc oxide is then reduced to metallic zinc by heating with carbon (coke) in a furnace:
      ZnO+C→1673 KZn+CO↑(carbon reduction)\text{ZnO} + \text{C} \xrightarrow{1673\text{ K}} \text{Zn} + \text{CO} \uparrow \quad \text{(carbon reduction)}
      Thus, this overall conversion involves both roasting and carbon reduction.
      Therefore, (C) matches with (p, r).

  4. (D) Cu2S→Cu\text{Cu}_2\text{S} \rightarrow \text{Cu}:
    The extraction of copper from copper glance (Cu2S\text{Cu}_2\text{S}) involves:

    • Roasting: Partial roasting of Cu2S\text{Cu}_2\text{S} in the presence of air to form cuprous oxide (Cu2O\text{Cu}_2\text{O}):
      2Cu2S+3O2→Δ2Cu2O+2SO2↑(roasting)2\text{Cu}_2\text{S} + 3\text{O}_2 \xrightarrow{\Delta} 2\text{Cu}_2\text{O} + 2\text{SO}_2 \uparrow \quad \text{(roasting)}
    • Self Reduction (Auto-reduction): The remaining copper sulfide reacts with the formed cuprous oxide in the absence of external reducing agents to produce metallic copper:
      2Cu2O+Cu2S→Δ6Cu+SO2↑(self reduction)2\text{Cu}_2\text{O} + \text{Cu}_2\text{S} \xrightarrow{\Delta} 6\text{Cu} + \text{SO}_2 \uparrow \quad \text{(self reduction)}
      Thus, this overall conversion involves both roasting and self reduction.
      Therefore, (D) matches with (p, s).

Final Matching:

  • (A) →\rightarrow (p)
  • (B) →\rightarrow (q)
  • (C) →\rightarrow (p), (r)
  • (D) →\rightarrow (p), (s)
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