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Multiple choice chemistry general principles of metallurgy extraction of copper and zinc extraction of copper and zinc from their oxides basics of metallurgy

Aluminium and copper are extracted from their oxide and sulphide ores respectively. Which of the following is correct ? 
I. Copper is extracted by the auto reduction of copper oxide by copper sulphide.
II. Aluminium cannot be obtained by chemical reduction due to its strong affinity for oxygen.
III. In electrometallurgy of $Al$, graphite is used as cathode to avoid reoxidation of $Al$ into $Al _2O _3$ by preventing formation of $O _2$.
IV. Sulphide ores of copper are difficult to be reduced than the oxide ores.

  1. $I , II ,IV$
  2. $II$ and $III$
  3. $III$
  4. $II$ and $IV$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In the electrometallurgy of $Al$, graphite is used as anode as oxygen being a non-metal is liberated at the anode and the reoxidation of $Al$ into $Al _2O _3$ is avoided.

Multiple choice chemistry general principles of metallurgy extraction of copper and zinc extraction of copper and zinc from their oxides basics of metallurgy

Which of the following steps correctly depicts the self-reduction of $Cu _2S$ to $Cu$?

  1. Roasting

  2. Smelting

  3. Bessemeriztion

  4. Poling
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In the extraction of copper, the self-reduction reaction of Copper taking place in a Bessemer converter is as follows:


$2Cu _{2}S+3O _{2} \rightarrow 2Cu _2O+2SO _{2}$

$Cu _{2}S+2Cu _{2}O\rightarrow 6Cu+SO _{2}$ (self reduction)

Option C is correct.

Multiple choice chemistry general principles of metallurgy extraction of copper and zinc extraction of copper and zinc from their oxides basics of metallurgy

STATEMENT-1: Extraction of zinc from sphalerite ore involves the roasting followed by reduction with coke.
STATEMENT-2 : Zinc can be commercially extracted by hydrometallurgy.

  1. STATEMENT-1 is True, STATEMENT-2 is True; STATEMENT-2 is a correct explanation for STATEMENT-1

  2. STATEMENT-1 is True, STATEMENT-2 is True; STATEMENT-2 is NOT a correct explanation for STATEMENT-1

  3. STATEMENT-1 is True, STATEMENT-2 is False

  4. STATEMENT-1 is False, STATEMENT-2 is True
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Sphalerite ((Zn,Fe)S) is a chief ore of zinc. It consists largely of zinc sulfide in crystalline form but almost always contains variable iron.
Extraction of Zinc follows:
Roasting followed by reduction with carbon; then electro-fining of Zn.

Hydrometallurgy:
In this process, desired metal is extracted from its solution by addition of more electro positive metal.
But there are very few metals which are more electro positive than Zn so it can not be extracted by hydrometallurgy

Multiple choice chemistry general principles of metallurgy extraction of copper and zinc extraction of copper and zinc from their oxides basics of metallurgy

Which of the following process(s) occur(s) during the extraction of copper from chalcopyrites?

  1. froth floatation

  2. roasting

  3. bessemerisation

  4. leaching
Reveal answer Fill a bubble to check yourself
A,B,C Correct answer
Explanation

In the extraction of copper, following methods are used
froth floatation
roasting
smelting
bessemerisation and 
electrolytic refining

Multiple choice chemistry general principles of metallurgy extraction of copper and zinc extraction of copper and zinc from their oxides basics of metallurgy

$Zn + NH _3 \quad\xrightarrow{\small{heat}} \quad ?$

  1. $ZnH _2 + N _2$
  2. $Zn _3N _2 + H _2$
  3. $Zn(NH _2) _2 + H _2$
  4. $[Zn(NH _3) _4]^{2+}$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Zinc(II) ion forms complex ions readily.
Reaction of the process:
$Zn + xNH _3 \quad\xrightarrow{\small{red heat}} \quad Zn(NH _3) _x$
Where $x = 4$ to $6 $ 

Multiple choice chemistry general principles of metallurgy extraction of copper and zinc extraction of copper and zinc from their oxides basics of metallurgy

In the extraction of copper, the smelt formed in the blast furnace contains:

  1. $Cu _{2}S\ +$ little $FeS$
  2. $Cu _{2}S\ +$ little $FeO$
  3. $Cu _{2}O\ +$ little $FeS$
  4. $Cu _{2}O\ +$ little $FeO$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In the extraction of copper, raw material used for the Bessemer converter is matte ($Cu _2S+FeS (little)$), where matte is formed in the blast furnace.

Multiple choice chemistry general principles of metallurgy extraction of copper and zinc extraction of copper and zinc from their oxides basics of metallurgy

Formation of metallic copper from the sulphide ore in the commercial metallurgical process involves:

  1. $Cu _{2}S$ $+\frac{3}{2} O _{2}$ $\rightarrow$ $Cu _{2}O+$$SO _{2}$ ; $Cu _{2}O$+$C$ $\rightarrow$ $2Cu$+$CO$
  2. $Cu _{2}S+$ $\frac{3}{2}O _{2}$ $\rightarrow$ $Cu _{2}O+$ $SO _{2}$; $2Cu _{2}O+$ $Cu _{2}S$ $\rightarrow$ $6Cu+$$SO _{2}$
  3. $Cu _{2}S+2O _{2}\rightarrow CuSO _{4}$; $CuSO _{4} + Cu _{2}S\rightarrow 3Cu + 2SO _{2}$
  4. $Cu _{2}S+ \frac{3}{2}O _{2} \rightarrow 2Cu+ SO _{2}$ ; $Cu _{2}O+CO\rightarrow2Cu+CO _{2}$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The commercial metallurgical process for the formation of metallic copper from the sulphide ore involves oxidation of $Cu _2S$ to $Cu _2O$  and auto reduction of a mixture of $Cu _2S$ and $Cu _2O$ to copper metal.

$Cu _2S + \frac {3} {2}O _2 \rightarrow Cu _2O+SO _2$

$2Cu _2O+Cu _2S \rightarrow 6Cu+SO _2$